PART 1: Considering the first anniversary of a new climate regime
Accelerating down the road to extinction in Earth’s Hothouse Hell?

(11 May 2024)

William P Hall^[1], PhD

Editor, Climate Sentinel News
@VoteClimateOne

13 March 2024 is the first anniversary of the global average sea surface temperature breaching the record high temperature for the day of the year and 2 days before breaching the previous all-time record. These breaches may be associated with the apparent exponential rise in Earth’s Energy Imbalance, i.e., the difference between the heat energy content of incoming solar radiation entering the atmosphere versus that of outgoing radiant energy (IR) from the Earth leaving the atmosphere.

Table of Contents

Table of Contents

Introduction

Earth’s Energy Imbalance

Why temperature is important

Earth’s energy balance sets the global average temperature

Measurements of Earth’s energy imbalance

Energy and carbon flows through the climate system set temperature regimes for Earth’s climates

Potential differences between energy sources and sinks drive energy flows.

Balancing the energy budget

Greenhouse gases and carbon cycle

Greenhouse gases regulate Earth’s energy balance

Earth’s carbon cycle

Impacts of Earth’s Energy Imbalance on the Biosphere

Most excess solar energy appears first in the world’s oceans

The atmosphere absorbs most of its excess heat energy from the ocean and transports it to polar regions and the land around the world.

Energy in heat and humidity transferred from the ocean to the atmosphere is distributed around the world by convective winds driving weather systems

Tradewinds and jetstreams

Temperature extremes and extreme weather

Arctic amplification and crazy jet streams

Sulfate aerosols and ‘termination shock’

How hot is too hot? Lethal heat and increasingly extreme weather

Introduction

For the last 20-30 years, our planet’s climates have been growing noticeably warmer, with each year on average slightly warmer than the previous year—perhaps setting a few new daily records each year. Other temperature-related climate variables also showed similarly creeping changes towards more extreme values. Last year, in mid-March, that familiar pattern began to “go crazy”. This is also the headline story told by the WMO’s (World Meteorological Organization) just published State of the Global Climate 2023 report.

Australia’s ABC News announced that the WMO’s climate report “...confirms 2023 broke every single climate indicator”. This isn’t journalistic exaggeration by the ABC, but rather simply states the conclusions from the considered analysis of a vast array of factual data on a variety of measures collected continuously by the many international organizations working together within the WMO. This data is processed, analyzed, and reported disciplined and consistently to support weather-dependent decisions and planning by individuals, organizations, and governments.

To facilitate understanding of the data by those who need it, the WMO developed “[seven] headline indicators for global climate monitoring. These … are a subset of the existing set of essential climate variables (ECVs) established by the Global Climate Observing System and are intended to provide the most critical parameters representing the state of the climate system….”

Figure 1.  Headline Indicators for Global Climate Monitoring

In the last year, these headline indicators and many of the other ECVs have markedly deviated in alarming ways from their previous behaviors over previous years. For example, my cover picture shows the day-by-day variation in two of the most important measures of global warming. These highlight the rapidly increased rate of warming in 2023, which is continuing today.

As the following pages will show, virtually every climate variable measured consistently over a history of more than a decade also began to go crazy, suggesting that the behavior of the whole climate system may be undergoing some kind of radical ‘breakdown’.

This behavior highlights that all of these measurements concern aspects of Earth’s Climate System. Climate is the primary example of a complex dynamical system of multiple interacting variables, where many interactions are non-linear, chaotic, or even undiscovered. Such systems may show ‘basins’ of semi-stable (and thus somewhat predictable) behavioral cycles, as Earth’s climate does. Even with basins of semi-stabillity, complex systems like this are mathematically intractable for modeling and fundamentally unpredictable. In cases where predictive mathematics is inappropriate, historical and comparative approaches provide rational methodologies for anticipating possible futures – especially in rapidly escalating crises.

The Intergovernmental Panel on Climate Change (IPCC) fails to incorporate this inherent unpredictability as a precautionary principle in its reports and recommendations^[2].

The WMO, the Secretary General of the UN, António Guterres, and a few other scientists and leaders have warned that we are rapidly running out of time to escape the climate Hell that the climate indicators show we are currently accelerating towards. That Hell is so dire that even the brave souls willing to shout “Fire!” are reticent to name what it is they dread – mass extinction.

In this essay, a series of images will show how the various climate indicators have changed over time, translate what the variations mean, and explain how they interact to form the climate Hell we are racing toward. Finally, I will show and explain that this Hell is almost certainly the global mass extinction of most of the complex life on Earth—including humans.

Note: what I present in the body of this essay are processed measurements of climate reality, not the modeled predictions of climate futures.

Figure 2. Headline indicators from State of the Global Climate 2023. Peter D Carter (Climate Emergency Institute) summarizes in a single slide the crazy variation of many of these climate indicators.

Earth’s Energy Imbalance

Why temperature is important

Humans form part of Earth’s Biosphere. We depend on its ‘services’ for life, and everything we do with our lives affects the Biosphere. Following Wikipedia,

By the most general biophysiological definition, the biosphere is the global ecological system integrating all living beings and their relationships, including their interaction with the elements of the lithosphere, cryosphere, hydrosphere, and atmosphere. The biosphere is postulated to have evolved, beginning with a process of biopoiesis (life created naturally from non-living matter, such as simple organic compounds) or biogenesis (life created from living matter), at least some 3.5 billion years ago. [My italics]

The biosphere is a very complex ‘engine’ driven by the spontaneous flow of energy from high potential (= low entropy) ‘sources’ to low potential (= high entropy) ‘sinks’. There are two sources: solar radiant energy (mainly visible light, but also some ultraviolet (UV) and short wavelength infrared (IR), and a very small amount of geothermal heat flow representing only 0.027% of Earth's total energy budget. The universal sink for entropic waste energy is outgoing longwave thermal radiation in the infrared band from Earth’s surface and atmosphere that is lost in outer space.

Living elements of the biosphere depend mostly on the availability and constant flow of biochemical energy derived from the photosynthetic reduction of CO₂ by water to form carbohydrates (e.g., sugar) in the formula:

Some microorganisms are able to use redox potential differences between different chemical elements to drive the chemosynthesis of sugars. However, whatever the sources and sinks for the potential differences driving the biochemical processes of life are, the rates of the processes are governed by ambient temperature.

Inorganic processes in the biosphere are also mainly driven by solar energy (in the form of sensible heat). For example, ocean currents and weather are basically heat engines that do physical work on the environment, e.g., to transport materials in processes such as erosion, making rivers flow, etc. Again, the rates and extents of these processes are governed by ambient temperatures.

Earth’s energy balance sets the global average temperature

Like a bathtub with an open drain that receives a constant flow of water from an open tap, where the water depth adjusts itself until the flow down the drain is equal to the inflow from the tap; the Earth System adjusts itself over time so that the amount of long-wave radiant energy leaving the planet is the same as the amount of solar radiant energy it receives at shorter wavelengths.  The amount of solar radiation striking the planet is relatively constant, but many things can affect the amount and quality of the radiant energy leaving Earth. The primary source of Earth’s radiant energy is blackbody radiation, determined by Earth’s average temperature.

In situations where Earth’s ability to radiate particular wavelengths of energy is blocked to some degree (e.g., by concentrations of greenhouse gases that are opaque to those wavelengths) Earth’s temperature will rise until enough energy is radiated at wavelengths the atmosphere is still transparent to. Similarly, if the Earth reflects more solar radiation its temperature will fall until absorbed solar radiation is again balanced by the amount of radiant energy being emitted by the Earth System.

If you have ever kept tropical fish in an aquarium, the aquarium system is a perfect example. It will most likely be equipped with an electric heater (normally consisting of a thermostat and a heating coil encased in a glass tube). The aquarium will be constantly losing heat to a cooler external environment over time (possibly hours depending on the size of the tank). When it falls below the set low temperature, the heating coil will come on and begin adding more heat to the tank, adding more heat than is being lost, causing the temperature to begin rising until the set high temperature is reached which turns the heating coil off. At the planetary level, we humans recognize these shifts in temperature as global warming and global cooling.

Please note that it can take many years for absorbed solar energy to work its way through the Biosphere before it is radiated back to space as blackbody radiation. This will be apparent as I work my way through the various climate indicators affected by changing planetary temperatures.

Measurements of Earth’s energy imbalance

Figure 3. The most important graph in this essay: Acceleration of Earth’s Energy Imbalance in the 21st Century. Leon Simons’ plot of NASA CERES’ data on the Imbalance. The measurements are influenced by weather and climate cycles, but clearly  the imbalance has grown by a factor of ~4 over the 22 years covered by the plot. This extends the observations first published by Loeb et al., 2021,. Satellite and Ocean Data Reveal Marked Increase in Earth’s Heating Rate. (Geophysical Research Letters).

Since the satellite era began around 1980 sensors have been put into orbit above Earth’s atmosphere by NASA’s CERES project to directly measure the incoming solar radiation and Earth’s outgoing radiant energy. These measurements determine Earth’s radiation budget (energy balance) quite accurately. How these measurements are made and used is explained by Montillet et al. (2023, Preface to monitoring the earth radiation budget and its implication to climate simulations: Recent advances and discussion. Journal of Geophysical Research - Atmospheres). Von Schuckmann et al. (2023, Heat stored in the Earth system 1960–2020: where does the energy go? Earth Systems Science Data) place this measure in the context of the overall Earth System.

To put this apparent acceleration in an Earth history context, Shackleton et al. (2023, Benthic δ¹⁸O records Earth’s energy imbalance in Nature Geoscience [behind a paywall]) measured oxygen isotopes in marine sediment cores. Calibration against the energy imbalance record provided a proxy measure for tracking changes in the energy balance back more than 150,000 years into the past. Leon Simons’s X-Twitter thread provides more detail on how this works. In Figure 4, I have annotated Leon’s version of the original graph of Shackleton, et al’s results with last year’s peak imbalance data and highlighted significant aspects of the graph.

Figure 4. Historical changes in Earth’s net energy balance over the last 150,000 years. Shackleton et al. 2023, presented by Leon Simons, and annotated by me show that in the last 50 years, the imbalance has skyrocketed to 5 X greater than any time in the last 150,000 years. X-axis is thousands of years, Y-axis is the deviation (i.e., anomaly) in the flux of energy away from a net balance between incoming and outgoing. Yellow shading represents a positive imbalance (more incoming than outgoing = net heating), while blue is a negative imbalance (= net cooling). Two major positive imbalances correspond to the Last Interglacial period and the Present interglacial.

Earth will continue warming at a rate that is in some way proportional to the value as long as Earth’s energy imbalance remains positive. It would seem that runaway warming has already well and truly begun—and this warming will continue to accelerate until the imbalance becomes negative. This state of accelerating rise will only need to continue for a few more years before global mass extinction, including humans, is certain (...if it isn’t already so).

Could this measure be wrong? Is it contradicted by other climate variables?

Energy and carbon flows through the climate system set temperature regimes for Earth’s climates

Potential differences between energy sources and sinks drive energy flows.

Unfortunately for our future, rapidly changing measures trace the existence and progress of energy flows through all aspects of Earth’s Climate System. Figure 5 shows how energy and carbon propagate through various components of the System.

Balancing the energy budget

Figure 5. Energy and carbon flows through Earth’s Climate System: See Wikipedia: Atmosphere; Geosphere – Earth below the atmosphere, comprising: Hydrosphere (mainly oceans), Cryosphere, Biosphere, and Pedosphere. Solar energy – mainly shorter wavelengths of radiant energy in the form of visible light. Atmospheric energy – energy contained in the mass of the atmosphere as sensible heat (molecular motion) and latent heat (the energy of vaporization a molecule of water requires to separate itself from a mass of water molecules; this is released as the heat of fusion when gaseous water vapor condenses into liquid). Ocean energy – energy contained in the mass of liquid water forming the hydrosphere, mainly in the form of sensible heat. Land energy – energy contained in the mass of the soil, soil moisture, and the biosphere in the form of both sensible and latent heat. Earth IR – radiant energy (mainly longer black body wavelengths emitted by the mass of Planet Earth carrying energy away to outer space. Yellow arrows – solar radiant energy from the Sun impinging on components of the climate system. Red arrows – energy transfers among components of the climate system (conduction, convection, radiation). Light blue arrows – energy transfers involving formation/release of latent heat. Black arrows – steps in the carbon cycle between the atmosphere and soil mediated by photosynthesis and burning/oxidization.

It may help to understand what forms the units of energy take. There are three major forms of energy to track:

1. Radiant energy: electromagnetic radiation (‘lightwaves’) including (a) temperature-dependent ‘blackbody’ radiation as determined by quantum theory spread continuously over a range of photon wavelengths (photons of shorter wavelengths carry more energy per photon than longer wavelengths) or (b) emission or absorption ‘lines’ of photonic energy at specific wavelengths due to nuclear or electronic transitions within individual atoms or molecules.

2. Sensible heat: kinetic energy of the physical vibrations and motions of atoms and molecules that can be transferred from particle to particle by direct physical contact (conduction); or by the physical movement/circulation of vibrating particles from one place to another (convection). Water has a specific heat capacity of 4.186 J/g°C, meaning that it requires 4.186 J of energy (1 calorie) to heat a gram by one degree C.

3. Latent heat: the potential energy that is absorbed or released as the physical state of a material changes from one form to another, (e.g., heat of fusion – for H₂O the amount of heat absorbed as a unit mass of ice is melted into liquid; or heat of condensation – for H₂O the amount of heat absorbed as a unit mass of liquid water is evaporated into water vapor (the gas). The heat of fusion for water at 0 °C is approximately 334 joules (79.7 calories) per gram, and the heat of vaporization at 100 °C is about 2,230 joules (533 calories) per gram.

Balancing the Earth’s account books for the Biosphere’s energy exchanges with the rest of the Universe is fairly simple, in that we only need to consider radiant energy as measured at the top of the atmosphere. Because space is a vacuum with zero heat capacity, there is no possibility for heat transfer by conduction. Heat carried by cosmic dust, meteorites, and gas molecules escaping Earth’s gravity from the top of the atmosphere might be considered to be a form of convection, but this represents such an infinitesimal fraction of radiant energy exchanged that it can be ignored (except in the case of exceedingly rare km sized asteroids – ‘dinosaur killers’….).

The only significant source of radiant energy received by Earth is our 5,800 °K Sun. This consists of the continuous blackbody spectrum combined with spectral lines for atomic transitions on the solar surface, with most of this energy concentrated over short wavelengths visible to humans. Empty space, having a blackbody temperature of ~4 °K is the sink for Earth’s emitted radiation. This energy again consists of continuous blackbody spectra plus spectral lines/bands of emissions for various molecular transitions in the atmospheric gases. This consists entirely of long-wave infrared well below what humans can see.

Because neither energy absorption nor emission around the planet is uniform in time or space, potential differences exist everywhere to establish energy flows among local sources and sinks. These flows drive climate change, weather, winds, currents, weathering & erosion, biological metabolisms, and so on. Energy within the biosphere only flows spontaneously from areas of higher potential to areas of lower potential, releasing entropic heat energy in the process (Second Law of Thermodynamics). Systems tend to evolve towards “steady states,” e.g., where the Biosphere emits as much energy in longwave IR to space as it receives in solar energy. Following the Second Law, spontaneous flows within the Biosphere always flow from sources of high potential to sinks of lower potential.

A fraction of the flowing energy may be used to do work. In addition to driving processes that change the physical fabric of the biosphere, some of the flowing energy is temporarily held in the system as sensible heat (measured as changes in temperature), converted to latent heat (e.g., as heat of fusion required to transform ice at 0℃ to liquid water at 0℃ or heat of vaporization required to transform liquid water to vapor at the same temperature), or even used to do chemical work, such as solar radiation driving photosynthesis.

The flow through Earth’s Biosphere of high potential radiant energy from the Sun at a temperature of ~6000 °K and the Earth’s emission of low potential long-wave infrared radiation to the ~ 4 °K of empty space that sets local and global average temperatures. This flow drives evolution and change within the Biosphere itself. Over time the biosphere‘s internal temperatures and energy flows spontaneously change and evolve to maintain an approximate balance between the input and output energy. The energy budget accounts for how this balance is achieved.

Figure 6. Earth’s energy budget. The global annual mean Earth's energy budget for the period, Mar 2000–May 2004 period (W m⁻²). The broad arrow bands indicate the net flows of energy between compartments of the Biosphere in proportion to their importance from where incoming short wavelength solar radiation strikes the top of the atmosphere to where long wave energy is emitted to space.  The graphic is from Trenbarth, et al., 2009, Earth's global energy budget (Bulletin of the American Meteorological Society). The article explains how the values were determined.

Earth’s energy supply is drawn from the solar energy striking it, which averages ~341 W m⁻². Approximately 102 W m⁻² is reflected away by atmospheric clouds and aerosol particles (~79 W m⁻²) and Earth’s surface – esp. snow and ice (23 W m⁻²). The remaining ~ 249 W m⁻² is absorbed by clouds (~78  W m⁻²) and Earth’s surface – mainly ocean (~ 161 W m⁻²). The energy absorbed in relatively high potential forms by the atmosphere and surface drives physical (mainly convective) and chemical (mainly photosynthetic and metabolic) processes within the Biosphere as per the Second Law of Thermodynamics.

Because Earth is surrounded by empty space energy can only be gained or lost via black- body radiation or by absorbing or emitting particular (spectral) wavelengths from specific atomic or molecular changes. Because of Earth’s very low temperatures compared to the surface of the Sun, outgoing radiation is in the form of long wavelength Infrared (IR). (This ignores minuscule energy exchanges represented by meteorites and cosmic dust falling into the biosphere and the slow loss of gas molecules from the top of the atmosphere).

Most of the ~239 W m⁻² of outgoing radiation escaping Earth is emitted by gas molecules, aerosols (187 W m⁻²), and clouds (30W m⁻²) near the top of the atmosphere. Another 22 W m⁻² emitted from the Earth’s surface passes upwards through the atmosphere to space without being absorbed or reflected back downwards by components of the atmosphere.

Many energy flows occur between different components within the planetary biosphere itself. These involve conduction, convection, and radiation.

Conduction occurs where the atmosphere is in direct contact with a solid surface (e.g., soil or ocean) or where an object (organism, etc.) is in direct contact with the atmosphere, hydrosphere, or pedosphere.

Convection in the form of rising air (thermals) carries 17 W m⁻² into the atmosphere, Evapotranspiration of water from the hydrosphere moves 80 wm2 into the atmosphere in the form of the water vapor’s latent heat of condensation. This energy is released in the atmosphere as sensible heat when vapor is condensed to liquid and precipitates back to Earth’s surface. 396 W m⁻² is emitted from the surface as longwave IR, mostly to be converted into sensible heat in the atmosphere, aerosols, and clouds. In turn, the warmed atmosphere re-radiates long-wave IR energy back to heat the surface.

Most importantly for the living components of the biosphere, a tiny fraction (0.9 W m⁻²) of the total energy flow within the biosphere is absorbed in the photosynthetic fixation of carbon into sugars that fuel organisms’ metabolism and growth. Their carbon-containing remains and feces are eventually incorporated into stable marine sediments and soils as fossil carbon.

Most of the excess energy transiting compartments of the Biosphere is held in the form of sensible heat.  Von Schuckermann et al. in their 2023 paper, Heat stored in the Earth system 1960–2020: where does the energy go? (Earth System Science Data) have calculated changes over time in the amount of energy held as sensible heat as a consequence of changes in Earth’s energy imbalances. These estimates are based on observed changes in temperature, ice volumes, and humidity.

Figure 7. Total Earth system heat gain in ZJ (1 ZJ = 10²¹ J) relative to 1960 and from 1960 to 2020. Most of the excess energy is stored in the ocean compartment. The upper ocean (0–300 m, light blue line, and 0–700 m, light blue shading) receives energy directly from other sources and accounts for the largest amount of heat gain, followed by the intermediate ocean (700–2000 m, blue shading) and the deep ocean below 2000m depth (dark blue shading). The land compartment  (orange shading) stores the next largest amount of the excess, followed by the gain of energy to melt grounded and floating ice in the cryosphere (gray shading) and the heating of the atmosphere (magenta shading). Uncertainty in the ocean estimate also dominates the total uncertainty (dot-dashed lines derived from the standard deviations for the ocean, cryosphere, land, and atmosphere).... The dataset for the Earth heat inventory is published at the German Climate Computation Centre (DKRZ; https://www.dkrz.de/, last access: 29 March 2023).... ”[W]e obtain a total heat gain of 381±61 ZJ over the period 1971–2020, which is equivalent to a heating rate (i.e., the EEI) of 0.48±0.1 Wm⁻² applied continuously over the surface area of the Earth (5.10x10¹⁴ m²). The corresponding EEI over the period 2006–2020 amounts to 0.760±2 Wm⁻²”.

According to von Schuckermann, et al., around 89 %, of the excess heat from the energy imbalance is held in the ocean, ~6 % on land, ~1 % in the atmosphere, with about 4 % available for melting the cryosphere. Two factors control the imbalance: (1) the percentage of solar energy that is reflected rather than absorbed (Earth’s albedo) and (2) the concentrations of greenhouse gases in Earth’s atmosphere that block Earth’s energy emissions at certain wavelengths: mainly water and carbon-based gases.

Greenhouse gases and carbon cycle

Greenhouse gases regulate Earth’s energy balance

Figure 8. Absorption coefficients of the main greenhouse gases (Wikipedia: Greenhouse gas - Rhwentworth).  This chart plots the absorption coefficient of some of the principal greenhouse gases for electromagnetic radiations with wavenumber values (i.e., frequency divided by the speed of light) in the range 200-1600 cm-1 (wavelengths in the range 6.25-50 microns). The gases considered include water vapor (H2O), carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4). While water vapor has the greatest overall absorption, carbon dioxide is important because it absorbs strongly around a wavelength of 15 microns, where the Earth emits much of its thermal radiation. Results are for sea-level atmospheric pressure, a water vapor concentration of 0.25%, and a CO2 concentration of 420 ppm, an N2O concentration of 390 ppm, and a CH4 concentration of 1900 ppb. These concentrations are roughly characteristic of atmospheric average values in recent years. Ozone is present in the troposphere but most significant in the upper atmosphere, so cannot readily be compared. Results are for sea-level pressure, but vary with altitude due to pressure broadening. Concentration of water vapor declines with altitude, increasing the relative importance of other gases at higher altitudes.

Figure 9 shows the absorption bands in the Earth's atmosphere (middle panel) and the effect that this has on both solar radiation and upgoing thermal radiation (top panel). Individual absorption spectra for major greenhouse gases plus Rayleigh scattering are shown in the lower panel. Both the Earth and the Sun emit radiation that closely follows a blackbody spectrum, and which can be predicted based solely on their respective temperatures. For the Sun, these emissions peak in the visible region and correspond to a temperature of ~5500 K. Emissions from the Earth vary following variations in temperature across different locations and altitudes, but always peak in the infrared.

Figure 9. Atmospheric absorption and scattering at different wavelengths of electromagnetic waves (Wikipedia: Greenhouse gas). The largest absorption band of carbon dioxide is not far from the maximum in the thermal emission from the ground (dark blue on the left), and it partly closes water vapor’s windows of transparency, accounting for much of carbon dioxide's heat-trapping effect.

The position and number of absorption bands are determined by the physical and chemical properties of the gases in the atmosphere. As far as the greenhouse is concerned, nitrogen and oxygen are transparent to both incoming and outgoing radiation. Water vapor is the most significant of these greenhouse gases, followed by the carbon gases carbon dioxide (CO₂) and methane (CH₄). Also, Rayleigh scattering, the physical process that makes the sky blue, disperses some incoming sunlight. Collectively these physical processes capture and redistribute 25-30% of the energy in direct sunlight passing through the atmosphere. Where outgoing radiation is concerned, greenhouse gases capture 70-85% of the energy emitted from the Earth's surface, raising surface and gas temperatures enough to broaden radiation bands and shift emission frequencies to higher energy levels toward a balance between incoming and outgoing radiation.

Because water molecules in the atmosphere are directly involved in transporting and transferring the heat energy generating weather, they constantly shift between gas, liquid, and sometimes solid (ice) phases. Changes in the concentration of water vapor are considered to be consequences rather than causes of Earth’s changes in energy balance. Changing concentrations of the carbon-containing molecules CO₂ and CH₄ provide the primary regulatory control over Earth’s energy balance.

Earth’s carbon cycle

Of all the chemical elements in the Universe, carbon is the most important for life. Not only is carbon the backbone element that along with hydrogen, oxygen, and nitrogen, makes life’s organic chemistry possible; but the biologically involved gases CO₂ and CH₄ regulate Earth's temperature to maintain a climate where life can thrive. Photosynthesis combines CO₂ and water (H₂O) to form potential energy-rich sugars. Energy released by oxidation of the sugars drives the formation of other organic carbon-based molecules synthesized from the sugars’ components along with other elements essential to life and its activities. Further oxidation of these products of life to low potential CO₂ and H₂O provides the energy that drives most life today. Some microorganisms have methanogenic metabolisms that use inorganic energy sources to combine CH₄ and H₂O to form sugars as fuel that is anaerobically ‘oxidized’ to low potential CH₄ and H₂O.

Earth’s active inventory of carbon continually cycles through the major compartments of the biosphere (Fig. 5). There is also a very slow geological exchange of carbon between the biosphere, pedosphere, and underlying lithosphere. Organic carbon from dead organic matter accumulates to form peat, coal, oil, and methane. Biologically produced carbonates (coral reefs, sea shells, shelly planktonic debris, etc.) form stable sediments that become rocks and trapped reservoirs of oil and ‘natural’ gas (see Wikipedia’s Geochemistry of carbon). Some CO₂ is also captured in carbonate materials formed by geochemical weathering. Tectonic movements, volcanism, and erosion may then expose the carbon incorporated into sediments and rocks to erosion and oxidation to join the active carbon cycle in the Biosphere as CO₂.

Figure 10 is a quantified animation by Robert Rhodes of the rapid biological and much slower geological carbon cycles. It specifically demonstrates the large human impact on the amount of actively circulating biological carbon since we discovered that we could mine and burn fossil carbon to drive their industrial activities. Based on Rhode’s numbers, in 1850 there were 1469 Gigatons of accessible fossil carbon (=GtC) on Planet Earth. By 2017 when his animation ends, 424 GtC of that reserve had been burned, or 28.86% of the total planetary reserve! 276 GtC of that to the atmosphere. Most of the remainder goes into the ocean.

Figure 10. Earth’s Carbon Cycle. Animated diagram by Dr Robert Rhode, Chief Scientist @BerkeleyEarth, of the Earth's Carbon Cycle and how it has changed over time. Carbon, in various forms including CO2 and organic materials, is continually exchanged between the atmosphere, oceans, and biosphere. However, human activities have perturbed the carbon cycle. Play the animation in this X-Twitter thread, posted in 2019,  where he answers many questions about data sources and what they show.

It took many millions of years for Earth’s geological processes to build the carbon deposits humans have burned at an ever-increasing rate since the early Industrial Revolution beginning around 1850. Much of the coal fueling the early days of the Industrial Revolution was formed around 320 million years ago in the Carboniferous era. Over the last ~170 years, the emissions from burning this carbon have built up in the atmosphere and other Biosphere compartments because the geological processes for recapturing the carbon into sediments have been vastly overwhelmed (Figure 11).

Figure 11. Combined components of the global carbon budget as a function of time for fossil CO₂ emissions (grey) and emissions from land-use change (yellow-brown), as well as their partitioning among the atmosphere (cyan), ocean (blue-grey), and land (lime-green). Panel (a) shown annual estimates for each flux, and panel (b) shows the cumulative flux (the sum of all prior annual fluxes) since 1850. The partitioning is based on nearly independent estimates from observations (atmosphere) and from process model ensembles constrained by data (ocean and land). The model estimates do not exactly add up to the sum of the emissions, resulting in a budget imbalance represented by the dotted red line (mirroring total emissions) and the fluxes from land, sea, and air reservoirs. All data are in Gigatons of Carbon per year (GtCyr⁻¹). Data sources and how they are processed are described in the source document: Global Carbon Budget 2022 in Copernicus’s Earth System Science Data by the Global Carbon Project.

The close correlation in this accounting between decreasing reserves of fossil carbon and increasing quantities of carbon gases in the atmosphere and other biospheric compartments clearly measures that the increases in active carbon in those other compartments are clearly consequences of the anthropogenic uses of that fossil carbon.

Figure 12. A simple comparison between global mean temperature and carbon dioxide. Dr. Roger Rhode on X-Twitter, 2021, shows the correlation between changing atmospheric CO₂ concentrations and changing global average temperatures.

Blocking part of Earth’s outgoing energy flow causes the excess energy to be held in the form of sensible heat in the atmosphere and other compartments of the Biosphere. In other words, humans are responsible for global warming!

Correlation suggests positive feedback interaction between atmospheric CO₂ concentration and global temperature

Figure 13. Similar growth patterns in both global average temperatures and atmospheric CO₂ concentrations supports positive feedback between the two phenomena is driving exponential growth in both. https://twitter.com/RogerCoppock/status/1773710044208750884 

The difference between the spectra of Earth’s incoming and outgoing energy together with the absorption spectra of the various molecular species in the atmosphere demonstrate the physical blockage of the energy flow causing global temperatures to rise. Initially, this was primarily a consequence of humans’ carbon mining and burning activities. However, the rate of growth in human contributions may have slowed (but not yet decreased), while the concentrations of critical greenhouse gases and global temperatures still seem to be rising exponentially. This suggests that heating-related natural emissions are growing to take up the slack (see the body of evidence in the remainder of this essay).

Figure 14 summarizes the rapidly growing and accelerating concentrations of the three main ‘natural’ greenhouse gases that are directly affected by human activities:  CO₂, CH₄, and N₂O. Assuming no changes in Earth’s reflectivity, global temperatures will not begin to drop until the annual increases shown in the right-hand set of charts of these gases drop to less than zero, (i.e., until their concentrations actually start decreasing).

Figure 14. Annual variation in the principal greenhouse gases controlling Earth’s energy balance. The graphs show monthly mean concentrations of CO₂, CH₄, and N₂O as measured at Mauna Loa Observatory, Hawaii, the principal station in the Carbon Cycle Greenhouse Gases (CCGG) research area within NOAA’s Global Monitoring Laboratory. The carbon dioxide data on Mauna Loa constitute the longest record of direct measurements of CO2 in the atmosphere. They were started by C. David Keeling of the Scripps Institution  of Oceanography in March of 1958 at a facility of the National Oceanic and  Atmospheric Administration. NOAA started its own CO2 measurements in May of 1974, and they have run in parallel with those made by Scripps since then.

Figure 15 shows measurements recorded at the Mauna Loa Observatory. These are compared to and aggregated with similar readings made by a variety of other instruments and laboratories around the world. See also CarbonTracker CT2022 for some excellent graphics and discussions of global and regional CO₂ and CH₄ budget measurements, uncertainties, models, maps, visualizations, and even animations–all current to 2022. The EU’s Copernicus Program provides comparable information via its Climate Indicators. The USA’s NOAA Research says “No sign of greenhouse gases slowing in 2023”.

Figure 15. Cooperative Measurement Programs participating in NOAA’s Global Monitoring Laboratory’s Carbon Cycle. See What is the Global Greenhouse Gas Reference Network? It provides a comprehensive array of information about how the measurements are made and validated and what they signify. See also https://gml.noaa.gov/ccgg/ggrn.php.

It now remains to explore (a) what happens as the excess solar energy held up in the Biosphere propagates through the compartments of the climate system from sources where solar radiation is initially received to sinks where the Biosphere emits longwave IR to outer space and (b) how life is being impacted by changes caused by the excess energy.

Impacts of Earth’s Energy Imbalance on the Biosphere

Most excess solar energy appears first in the world’s oceans

Earth is a water planet: Oceans cover about 70% of its total surface. According to Schuckermann et al, (2023)--Figure 7, here, 89 % of the excess solar energy causing the energy imbalance is held in the ocean as sensible heat. The land holds about 6 %, the atmosphere 1 %, and about 4 % melts the cryosphere. Because this flood of excess heat raises ocean temperatures, new daily records have been set every day without a break for 393 days so far, suggesting that Earth’s Climate has passed a critical threshold into a new and vastly more dangerous climate regime than we have been living in for the last 10,000 years (Fig. 16). The Washington Post noted that “Scientists fear planetary shift as record ocean heat enters second year - Warming trend could represent a major change to Earth systems that cannot be reversed on any human time scale”

Figure 16. Daily variation in the global average sea surface temperature for every year from 1981 until Friday, 5 April 2024. ClimateReanalyzer began plotting daily averages of sea-surface temperatures in 1981, at the beginning of the satellite era. This plot excludes the polar oceans, which are largely ice-covered. ClimateReanalyzer explains how the data are sourced and plotted.

Solar light energy strikes Planet Earth at a relatively constant rate. However, because Earth is a sphere rotating on a tilted axis following an elliptical orbit around the sun the amount received over a given area varies considerably through daily and yearly time and location on the globe. This is called insolation and is purely a consequence of the astronomical relationship between Earth and the Sun (see Wikipedia for details).

Local sea-surface temperatures (Figure 17) are a consequence of the local energy imbalance between, (a) radiant energy received by insolation + other energy received via convection and conduction, and (b) energy lost by longwave IR to space + other energy lost via convection and conduction. “Other energy” may be in the form of sensible or latent heat. Conduction involves the movement of heat through stationary matter at a molecular level so it can be ignored where weather and climate are concerned. Convection may involve latent heat as well as sensible heat and is driven by the physics of the Second Law of Thermodynamics declaring that systems can only spontaneously evolve toward thermal equilibrium or at least a steady state of maximum entropy. This tendency to change towards equilibrium/steady state powers the heat engines of weather and climate. Ocean currents and atmospheric winds form spontaneously to carry energy from warmer places to cooler places, which necessarily draws cooler air or water in to replace the currents that have flowed away. The greater the energy imbalance, the more forceful/extreme the resulting winds and currents will be. Note: currents and winds may be predominately horizontal (e.g., Gulf Stream, Humbolt Current; trade winds, jet streams), predominately vertical (upwellings, downwellings; updrafts, downdrafts), or both horizontal and vertical (Thermohaline Circulation; cumulonimbus, storm cell, cyclone). See Leon Simons’s long and important X-Twitter thread from 11 March, on the role of aerosols on ocean heating and global warming in general.

Figure 17. Ocean temperatures on April 5, 2024, about three weeks after the Equinox, moving towards the Northern Hemisphere’s summer. Upper: ocean temps. Lower: temperature anomalies. ClimateReanalyzer, 10 Apr 2024.

Energy absorbed into the ocean raises water temperature in proportion to any excess over the long-term average absorption. Currents carry this relatively hot water to warm cooler areas increasing average temperatures there as well.

Over the entire ocean, the water tries to cool itself via temperature-related transfers of heat to outer space (longwave IR) and the atmosphere (longwave IR from the ocean absorbed in the atmosphere and convective transfer of sensible heat to air molecules and latent + sensible heat in the form of water vapor).

Figure 18. Changes in ocean heat content since 1957 reflect the rapidly increasing imbalance in Earth’s energy budget shown in Figure 3–(Wikipedia - Ocean heat content) Note: the Wikipedia article offers an excellent explan- ation of how the heat is measured and calculated and its significance for climate change.

The plots of ocean heat content in Figure 18 are based on a wealth of measurements collected by the Argo program since ~1980. The primary tool for measuring heat in the entire volume of the ocean is the Argo floats. These are supported and calibrated by a multinational fleet of oceanographic vessels, commercial and other ships, surveillance aircraft, and moored buoys supporting a string of sensors all the way to the ocean bottom. Surface temperatures are calibrated and coordinated with a variety of global satellite sensors. Most floats are designed to measure profiles of the top 2000 m of the ocean, some very high-pressure varieties are designed to take measurements from bottom to top of the ocean. A Technological Innovations page describes the range of floats designed to measure a wider range of ocean parameters, to go deeper, and to safely work in ice-covered polar waters

Figure 19. Latest locations of 3879 operational Argo floats in January 2024 - About Argo: International Cooperation. Colored dots indicate the last recorded locations of floats operated by each participating country.  

The atmosphere absorbs most of its excess heat energy from the ocean and transports it to polar regions and the land around the world.

The World Ocean circulates heat energy to all corners of our planet. John Nelson’s map of Cool and Warm Currents on the Spilhaus ocean-centric map projection makes this particularly clear: All the waters of the Atlantic, Indian, and Pacific Oceans are connected by the Antarctic Current. Nelson also provides an animated Spilhaus projection, of annual variation in sea surface temperatures from 9/2018-8/2019 that serves to demonstrate the thermal gradients driving the ocean circulation shaped by land barriers and the Coriolis force from Earth’s rotation.

Figure 20. Cool and warm currents. The Spilhaus world ocean map in a square or "Spilhaus projection" is now available in ArcGIS Pro 2.5 (ArcGIS 10.8)  as the WGS 1984 Spilhaus Ocean Map in Square projected coordinate system.

Figure 21. The EU’s Copernicus Climate Pulse plot of daily variations in global average sea surface temperatures from 1979 through 11 April 2024. Note that this plot, compared with the American Climate Reanalyzer plot (Figure 16), is independently calculated from the raw data and differs in the exact average temperatures for many days. Nevertheless, both plots totally agree that in March 2023 sea surface temperatures began skyrocketing higher than any previous temperatures recorded; and where 2024 is concerned, these are substantially higher than 2023’s previous records.

Earth’s energy imbalance has been driving sea-surface temperatures higher at an accelerating rate as shown in Figure 21. The rapidly increasing heat content added to the oceans by the rising sea-surface temperatures is most obvious in the tropical and subtropical regions of the world. Following physical law, the dissipation of entropy in sensible heat as waters cool drives currents from warmer places to cooler ones, drawing in cooler water to again be heated by solar energy. Where water is warmer than air, some of the energy is transferred to the air as sensible heat and humidity.

Figure 22. Copernicus’sClimate Pulse chart (a) of sea-surface temperature (absolute values) on 10 April 2024 shows where the greatest heat is located; (b) Sea Surface Temperature percentiles for March 2024 shows where the greatest heat was being absorbed while the Sun was directly over the Equator. Dark red shades show areas with the highest monthly average temperatures on record. 

Energy in heat and humidity transferred from the ocean to the atmosphere is distributed around the world by convective winds driving weather systems

Figure 23. All-time daily record global average surface (2m air) temperatures for 2023 and 2024 up to 11 April, 2024, Copernicus Climate Pulse. See also Copernicus: March 2024 is the tenth month in a row to be the hottest on record.

Vertical and horizontal temperature differences in the atmosphere drive weather and climate change. Because most heat loss is from the top of the atmosphere, this is always colder than ground temperatures below the greenhouse layers, creating a temperature gradient where columns of rising warm air establish convection cells drawing cooler air to lower elevations to replace the rising warm air. In general, larger temperature differences lead to faster and more powerful updrafts and downdrafts contributing to increasingly extreme storms and weather systems. Also, given that Earth’s polar regions slope away from the Sun, they receive much less insolation than equatorial regions that are normally close to flat on to sunlight. Thus the poles are always colder than the equatorial regions, leading to latitudinal winds convecting heat received near the equator to polar regions. The Coriolis effect turns latitudinal winds into cyclonic winds. A National Geographic Society video demonstrates this. Putting the horizontal and vertical effects together you can begin to understand how the atmosphere’s attempts to equilibrate temperature differences turn simple convection cells into cyclones and hurricanes.

Increasing humidity resulting from higher ocean temperature substantially accelerates the convection from temperature differences alone. As water warms its evaporation rate (changing from liquid phase to vapor phase) rises. To evaporate a given weight of water from the surface of a body of water takes more than five times the energy required to heat the same quantity of water from 0 °C to 100 °C. This heat energy (known as the latent heat of vaporization)  is drawn from the body of the liquid water. Also, the maximum amount of water that air can hold as vapor (i.e., saturation vapor density) increases by about 7% for every ℃. When air cools below the saturation vapor density for the amount of vapor it is carrying, the water begins to precipitate as a mist of water droplets, releasing its latent heat energy as sensible heat–raising the temperature of the surrounding air mass. The boost of warmth drives the air mass higher, while the precipitated water droplets join up to form rain, snow, and hail, forming downdrafts and cooling lower levels of initially warm air to increasingly strengthen downdrafts.

Even small increases in temperature and humidity can lead to substantially stronger storm cells and cyclones.

Tradewinds and jetstreams

Figure 24. Major convection cells transport heat around the planet to fuel weather and climate change. Upper Left - Locations of the major latitudinal cells and directions of their surface winds. Upper right - Normal locations of the jet streams. Bottom - Latitudinal cross-section of the lower atmosphere where weather is generated (the Troposphere). See Wikipedia: Atmospheric circulation, Hadley cell, Jet stream.

Figure 24 identifies the major wind streams convecting heat around Planet Earth, from East to West, North to South, and from sea level to the top of the tropopause. These provide the rapid transport systems for moving heat (both sensible and latent) and water around the planet—locally, regionally, and globally—to make weather and climate. As noted above the main source of heat and water is the solar energy received and stored in the circulating mass of the world's ocean. Smaller amounts come from the land via the conduction of heat from the surfaces and the evapotranspiration of water and the radiation from plants and surfaces. Where weather over land is concerned, the local sources of heat and humidity can be quite important in governing local winds and precipitation.

As global average temperatures grow ever higher as a consequence of the imbalance between solar energy received and long-wave infrared via the top of the atmosphere, weather unavoidably becomes more extreme. This is because the energy difference available to drive storms from temperature differences and latent heat from the condensation of water vapor into precipitation becomes substantially greater for each degree increase in the temperature differences.

Temperature extremes and extreme weather

According to Copernicus Climate Change Service’s Global Climate Highlights—2023, global average temperatures are rising significantly year-on-year and have probably been doing so at an accelerating rate recently.

Figure 25. Surface Air Temperature Anomaly • 2023. Surface air temperature anomaly for 2023 relative to the average for the 1991–2020 reference period. Data: ERA5. Credit: C3S/ECMWF  Copernicus Climate Change.Service, 2024.

The European Centre for Medium-Range Weather Forecasts (ECMWF) “is a research institute and a 24/7 operational service, producing global numerical weather predictions and other data for our Member and Co-operating States and the broader community. The Centre has one of the largest supercomputer facilities and meteorological data archives in the world. Other strategic activities include delivering an advanced training and assisting the WMO in implementing its programmes. We are a key player in Copernicus, the Earth Observation component of the European Union’s Space programme, offering quality-assured information on climate change (Copernicus Climate Change Service), atmospheric composition (Copernicus Atmosphere Monitoring Service), flooding and fire danger (Copernicus Emergency Management Service)”

ERA5 is the fifth generation ECMWF reanalysis of the global climate and weather for the past 8 decades. Data is available from 1940 on. ERA5 is a state-of-the-art numerical climate/ weather modeling framework that incorporates surface, radiosonde, and satellite observations to estimate the state of the atmosphere through time, as detailed by Copernicus. Figure 26 compares ERA5’s record with four other independent collections of temperature records:

• NASA - Goddard Institute for Space Studies affiliated with the Columbia University Earth Institute. The GISS Surface Temperature Analysis version 4 (GISTEMP v4) is an estimate of global surface temperature change. Graphs and tables are updated around the middle of every month using current data files from NOAA GHCN v4 (meteorological stations) and ERSST v5 (ocean areas), combined as described in our publications Hansen et al. (2010) and Lenssen et al. (2019). 
• NOAA National Oceanic and Atmospheric Administration (NOAA) maintains the Global Historical Climatology Network (GHCN-Monthly) database containing historical temperature, precipitation, and pressure data for thousands of land stations worldwide. Also, NOAA's National Climatic Data Center (NCDC) of surface temperature measurements maintains a global temperature record since 1880.
•  HadCRUT (formed by combining the sea surface temperature records compiled by the Hadley Centre of the UK Met Office and the land surface air temperature records compiled by the Climatic Research Unit (CRU) of the University of East Anglia).
• Berkeley Earth provides high-resolution land and ocean time series data, gridded temperature data, incorporates more temperature observations than other available products, and better coverage. Global datasets begin in 1850, with some land-only areas reported back to 1750.

Figure 26. Global temperature data adjusted “to remove … the influence of factors we knew were only temporary, and not man-made. Specifically, these are volcanic eruptions (whose aerosols cool the planet), the El Niño Southern Oscillation (ENSO, which warms the world in its positive El Niño phase and cools in its negative la Niña phase), and solar variations (when the sun gets hotter or colder, so does the Earth). These exogenous factors make global temperature fluctuate, but don’t really get anywhere; removing their influence makes the global warming part clearer.” (Grant Foster in Open Mind). Stefan Rahmstorf, Head of Earth System Analysis @ Potsdam Institute for Climate Impact Research & professor of Physics of the Oceans @ Potsdam University was a coauthor with Foster of an earlier version of this graph (        Foster & Rahmstorf, 2011. Global temperature evolution 1979–2010). Rahmstorf posted this graph to X-Twitter: “This is what #globalwarming looks like if you remove the effect of El Niño, volcanic eruptions, and solar activity. The author [Foster] is a professional statistician with much experience in climate data analysis. The method is described here: https://tamino.wordpress.com/2024/02/16/adj

RCraig09’s Wikipedia graph below (Figure 27) compares these plots of global average annual temperatures, together with the Japan Meteorological Agency JRA-55 reanalysis product.

Figure 27. Measured global average temperature data from several scientific organizations is highly correlated. (In this chart, the "0" value is the average temperature from 1850 to 1900, which is considered the "pre-industrial" temperature level.)

I include this detail here to demonstrate that different organizations around the world get similar results because they all measure the same reality. Their analyses show a rapid and probably accelerating rate of global warming because the world is actually warming rapidly at what is probably an accelerating rate. As the global average temperature continues to rise, so does the energy available in the form of temperature differences (sensible heat) to drive the engines that we see as weather and storm systems.

Thanks to the physical properties of water vapor, warm air can hold 7% more water as a gas for every ℃ of temperature rise. Also, at biological temperatures (i.e., 25 ℃)  water vapor holds an awesome amount of latent energy that it must release as sensible heat when the vapor condenses into liquid water (580 calories for every gram of H₂O), compared to the amount of energy released by cooling already liquid water by 1 ℃ (1 cal/gm - by definition of calorie as a unit of measurement). Note: parcels of atmospheric gas expand and cool as they rise in the atmosphere. As the parcel cools below its dew point (its saturation point for a given pressure), gaseous water releases its heat of vaporization as the independent molecules begin to condense together as aerosol droplets of liquid water (or even ice crystals if the temperature is low enough). Aerosol particles begin clumping to form heavier droplets of rain, snow, or hail. The latent heat released by the condensation drives humid updrafts higher into ever colder layers of the atmosphere - ultimately turning all of the available humidity into rain, snow, and ice that falls out on the land.

This is how just a few degrees increase in temperature can change gentle rain showers into raging storms, cyclones, storm cells, cyclones/hurricanes, and the global circulation cells shown in Figure 24. Also, as air temperature rises, dry winds rapidly become ever more thirsty - with an increasing capacity to turn fertile moist soils into drought-stricken dust bowls. The growth of ever more extreme storms is considered in more detail further below.

Arctic amplification and crazy jet streams

Jet streams are fuelled by converging latitudinal winds where the the major circulation cells meet (Figure 24). The temperature differences between equatorial and polar regions provide the energy, and the Coriolis effect turns northerly and southerly winds towards the east.

Figure 28. Formation of the Polar Jet Stream in the context of Northern Europe. (Image: Ian Bott, FT Research via GO GREEN @ECOWARRIORSS on X-Twitter 13/08/2022.

Organization and wind speeds of jet streams are somewhat proportional to the temperature-related energy differences between tropical and polar air masses. At preindustrial temperature differences, both polar and subtropical jets are high speed (up to 400 kph) and relatively straight easterly winds.

The presence of an atmospheric greenhouse effect subject to global warming leads to an amplification of polar temperatures compared to the tropics. Arctic temperatures have risen about 4 x faster than the global average, reducing the energy available for jet streams The streams slow and meander widely, become quite chaotic as shown in Figure 25, or even die out completely to be replaced by local convection cells.

Figure 25. Northern Hemisphere jet streams in a chaotic jumble  on 20 April 2024, putting Northern Europe into Arctic  deep-freeze. Earth.Nullschool.Net.

Figure 25 shows many deep north-south meanders (ref. Rossby waves). Frigid Arctic air is held on the north side of the jet stream, and warm to hot subtropical air in on the south. Where the stream meanders far to the south, frigid air follows from the north and vice-versa for warm southerly air. For example, in the figure showing the location of jet stream activity on 20 April 2024 one southerly meander extends as far south as Greece, and a northerly meander extends as far north as central Alaska and an edge of the Arctic Ocean. Because they are associated with slowing winds these extensive meanders may be stationary as ‘blocks’, preventing the normal west-to-east movement of weather systems - thus holding extremely hot (i.e., heat domes) or cold weather (cold waves) more or less stationary in one area for days or even weeks (see also polar vortex). The chaotic wind systems allowed by a weak polar jet stream act as positive feedback by carrying hot and humid tropical air into the Arctic enabling warm(ish) rain to amplify Arctic warming and speed the melting of polar ice and snow.

Sulfate aerosols and ‘termination shock’

Figure 27. Total sulfate (parts per trillion by volume) and percentage of total sulfate provided by shipping in simulations of Jin et al. [157] prior to IMO regulations on the sulfur content of fuels. Earth’s albedo (reflectivity) measured by CERES (Clouds and Earth’s Radiant Energy System) satellite-borne instruments [81] over the 22 years March 2000 to March 2022 reveal a decrease of albedo and thus an increase of absorbed solar energy coinciding with the 2015 change of IMO emission regulations.

Not all of the heating indicated by Figures 25 and 26 does not necessarily reflect a simple relationship to rising concentrations of greenhouse gases. Leon Simons in several X-Twitter threads has made a very good case (also in conjunction with Stefan Rahmstorf) that the sudden cessation of sulfate aerosol emissions from worldwide shipping has significantly reduced Earth’s reflectivity/albedo. In other words, solar energy that has previously been reflected away is penetrating deeper into the atmosphere where it too has been trapped within the ‘greenhouse’, adding to the heating that was already occurring – probably by enough to account for the latest upward acceleration in global average temperatures (see Simons’s latest thread). James Hansen, et al. discuss this in their 29 March newsletter from the Climate Science, Awareness and Solutions program, Earth Institute, Columbia University.

There are two lessons that can be drawn from this unintended experiment with geoengineering: (1) The global warming caused by anthropogenic greenhouse gas emissions was already worse than we imagined. (2) Adding reflective aerosols to Earth’s atmosphere can substantially reduce the overall imbalance between the energy Earth absorbs from insolation and the energy Earth emits as longwave IR.

However, although sulfate aerosols effectively reflect solar energy, it would be bad news for life on Earth if we added to the pollution they already cause. “Sulfate aerosols” actually consist of microscopic droplets of water formed when water vapor reacts with the sulfate ion to form sulfuric acid that falls out within months of forming onto the land and sea, making both significantly more acid than is healthy for living things.

Although far too little research has been done to date, several other less toxic elements, e.g., calcium, can also be added to the atmosphere as aerosols that should also be effective reflectors for solar radiation. Wikipedia’s article, Stratospheric aerosol injection is a useful introduction.

How hot is too hot? Lethal heat and increasingly extreme weather

One of my teaching subjects as an evolutionary biologist was biogeography (a major stimulus for my interest in climatology). Basically, this involves developing a scientific understanding for why each species lives where it does on our planet rather than in other places where it cannot be found. Basically there are three major categories of explanations: (1) historical (where the species existed in the past and the availability of habitable routes through geological time and space to where it exists now); (2) ecological (the species must be better at surviving in at least some part of the potentially habitable area than all other species with access to that area); and (3) genetic/evolutionary (every species has its genetically determined limitations that determine conditions for a habitable environment that must be met for it to be able to survive and reproduce) – e.g., the species must be able to survive all climatic variations encountered in its environment.

All life as we know it is based on water-based chemical reactions that are normally all involved in long chains of catalyzed reactions necessary to provide particular chemical products where and when they are needed to sustain life (Figure 28). The chemistry simply will not work without adequate water. Also, for thermodynamic reasons all chemical reaction rates are strongly affected by temperature changes – with no requirement that the rates of any two reactions will necessarily change in the same way with the changing temperature. Finally, given that biological catalysts (‘enzymes’) are complex organic molecules they are denatured with rising temperatures to become completely non-functional.

Figure 28. The changing rate of a chemical reaction catalyzed by an enzyme. (Wikipedia) Enzymes achieve an optimal rate of reaction at an intermediate temperature since increasing temperature increases activity, but above a certain temperature, they unfold (denaturation) to lose all catalytic functions. Below the optimal temperature the reaction rate generally increases at a fairly constant rate (= Q10)  for every 10-degree rise in temperature.

The temperature at which denaturation of essential proteins begins sets an absolute upper thermal limit to survival for most organisms. However, most organisms tend to live best just below this upper limit, because the optimal temperature for most of their enzymes is where their metabolism functions best, many species tend to live best at or just below this optimum.   In most organisms today, denaturation of enzymes and other essential proteins begins somewhere between 40-55 ℃. Over evolutionary time, natural selection may lead to adaptive changes in the thermal tolerances of biologically important proteins, but in general, this kind of change would have to involve coordinated changes to thousands of genetic loci; something that would take several to many thousands of generations to achieve.

Historically, over the last 2½ million years or so, life has primarily lived in a substantially cooler, glaciated world interspersed with periodic and generally short interglacial periods with temperatures comparable to today’s. Today we are living in an interglacial period that began only around 11,700 years ago, separated from the nearest previous interglacial (the Eemian) by more than 100,000 years of glaciation. Physiologically, we will be far better adapted for glacial times, rather than we are adapted to the historically extreme temperatures of the short period of the present interglacial, and with still accelerating global warming, we are racing towards physiologically lethal climate conditions our distant primate ancestors last encountered some several millions of years ago.

Figure 29. Maximum temperature for Perth, Western Australia on 18 February 2024, as reported on X-Twitter by  Prof Ray Wills  @ProfRayWills #IsItHotRightNow? #Perth 18Feb2024: Max 43.2°C Min 36.5°C Daily average 39.9 °C - hotter than 100% of days 1910–2021 “Hottest ever Yeh - check out the plots- off the chart”. Left: actual records for the 14 days around the designated date. Right: frequency distribution. Both are annotated to highlight that the apparently unrelated marks to the right of each chart do, in fact, belong to the the charts. The temperature was that extreme.

A weather map (Figure 30) shows temperatures for 18 February from the Shark Bay region farther up the Western Australian coast from Perth. Even more extreme temperatures for the day were recorded at the Shark Bay (49.8 ℃) and Canarvon Airports weather stations (49.9 ℃). Satellite reanalysis shows large areas inland of near-shore airports were off the color scale provided, which would have put them in the > 54 ℃ range! Fortunately, the heat wave was in an area of low human population and didn’t stall so the peak temperature only lasted for a few hours. This didn’t overstress the electrical network so people could easily shelter in air conditioned comfort, but I would not be surprised if there were mass die offs of marine organisms in Shark Bay’s World Heritage 5,000 km² seagrass ecosystem.

Figure 30. Temperatures reached close to 50 degrees over parts of WA’s Gascoyne and Central West, setting new town records over the region, and ranking in some of Australia’s hottest temperatures ever recorded. Canarvon tied 8th hottest temperature ever recorded in Australia (any month); Hottest day ever recorded at the town, with records dating back to 1883. The highest temperature recorded in the world so far in 2024.  (WeatherZone)

There have certainly been dieoffs of terrestrial vegetation as a consequence of this heating episode, as detailed in a Murdoch University news report: The big dry: forests and shrublands are dying in parched Western Australia.

Given that the majority of human evolution took place over the last 2½ million years during glacial periods and that we are now living in interglacial conditions at peak temperatures as hot or hotter than any time previously in that 2½ million years, we humans are already living at close to or even beyond our thermal optimum (ref. Figure 28).  Heat death from still- accelerating global warming is already a significant existential risk for a substantial fraction of the human species living in tropical and temperate regions of the world. Three accurate and useful articles drive this point home:

• Steven Sherwood, UNSW 2023 – How dangerous is extreme heat to humans?;
• World Health Organization 2018 – Heat and health (Fact Sheet);
• Ayesha Tandon, Prevention Web (UNDRR) 2023 – Risk of heat-related deaths has ‘increased rapidly’ over past 20 years.

Maximum temperatures (as observed this year in Western Australia - Figures 29 and 30) are already well into the lethal range, especially when combined with high humidity. It is only a matter of time before we see more than a million deaths when a heatwave stalls over a major metropolis (e.g., Seattle Washington 2021, Phoenix Arizona 2023, & Rio de Janeiro, Brazil this year, and the power system fails catastrophically because it is totally overloaded. It is only a matter of a year or two before we see the kind of mass death catastrophe Kim Stanley Robinson describes in Chapter 1 of his utterly realistic 2020 sci-fi novel, The Ministry for the Future (excerpted in Orion Magazine). Warning: the chapter is a gut wrenching and probable first-person account by a health worker who only barely survived himself. There are many multimillion inhabitant urban areas across Earth’s humid tropics where Robinson’s scenario could happen today with a completely plausible alignment of chance events. Every 0.1 ℃ rise in global average temperature significantly increases it’s likelihood. Will Robinson’s horrific vision come true this year? (Figure 31).

Figure 31. Maximum temperatures for Mon. 6 May, 2025. (ClimateReanalyzer)

As I write this) 7 May looks the same. On 7 May daily average temperature over E Pakistan and NW india is 39-40 degrees. Fortunately for inhabitants, the humidity is currently low, allowing evaporative cooling through sweating. Nevertheless, these temperatures are highly debilitating making physical work essentially impossible, but not immediately lethal.