Climate change's acceleration set to be exposed in coming decades as 'masking' impact of aerosol on greenhouse gases reduces

Sky News AU

5 days ago

Climate change is accelerating faster than previously thought, with Earth proving more sensitive to greenhouse gases than expected, new research has revealed.
Satellite data from NASA suggests that the worst-case climate models may actually be the most accurate.
Sky News Weather Meteorologist Rob Sharpe has explained what the latest research means for the planet.
Earth's energy imbalance - a growing concern
For most of human history, the Earth has absorbed about as much heat energy from the sun as it emitted back into space.
This has changed drastically in the past 20 years.
On the graph below, the black line shows the average solar radiation (heat energy) being absorbed by the earth across a four-year period.
It rises from 0.4 watts per square metre in 2000-2004 to 2.2 watts per square metre in 2021-2025.
Meanwhile the red line shows the amount of energy sent back into space in the form of long wave radiation.
This has undergone a similar but smaller rise since 2016.
The widening gap between these lines highlights Earth's energy imbalance - meaning our planet is now absorbing more energy than it emits.
Essentially Earth is now absorbing more energy than it is emitting into space - therefore getting warmer.
In just over 20 years, the imbalance has multiplied 3.5 times according to NASA's CERES satellite data.
The most recent estimate is 1.4 watts per square metre, which equates to a staggering 710 trillion watts (7.1×10¹â´ watts) – equivalent to the energy of 11 Hiroshima bombs every second.
That's a scary amount of extra energy being absorbed by our planet and not sent into space.
Almost all that energy is taken up by the oceans – almost 90 per cent.
Much of the rest of the energy is taken up by land and ice.
The atmosphere (air) only absorbs about two per cent of the huge energy imbalance – meaning that we don't easily notice the changing climate.
Scientists are clear that greenhouse gases are a substantial contributor to the change.
However, it's not the only contributor to watch. Greenhouse gases vs aerosols
There are two main types of pollution in our skies: greenhouse gases and aerosols.
When we talk about aerosols we're not merely talking about spray cans.
Aerosols—tiny particles suspended in the air—come from sources like bushfires, industrial activity, and dust.
They include sulfates, nitrates, and black carbon.
Most of these tend to cool the planet by blocking the solar radiation from reaching the earth's surface.
However, we don't know their full impact.
This is due to how many different aerosols there are, their complex interactions with the atmosphere (especially clouds) and challenges in measuring and modelling.
Further to this, until recently, they were steadily increasing in our atmosphere at a similar rate to greenhouse gases – helping offset some of their warming.
Their similar rate of change made it exceptionally hard for scientists to quantify the warming from greenhouse gases and the cooling from aerosols.
However, the number of aerosols in the atmosphere stopped increasing in 2000 and started a noticeable downward trend just before 2010 as the world improved air quality.
Meanwhile, greenhouse gases continue their rise.
The theory goes that the cooling influence of aerosols is waning – allowing temperatures to rise even faster and help scientists quantify their respective roles more accurately.
Most climate scientists now argue that global warming has accelerated in the past 15 years compared to the trend between 1970-2010 as shown in the graph below.
New research suggests that this upward trend could just be the beginning.
Earth is more sensitive than we thought
Climatologists rely on many models to predict how the climate will evolve.
These models are adjusted to account for uncertainties in Earth's climate system.
A team of scientists have released a paper in Science analysing the accuracy of these climate models when it comes to earth's energy imbalance and the role of air pollution from aerosols and greenhouse gases.
Essentially, they found that models that were more responsive to changes in greenhouse gases and aerosols were better at predicting Earth's energy imbalance.
In the chart below, dots closer to the top represent models predicting a stronger increase in incoming solar energy.
Dots on the left predict a stronger increase in Earth's outgoing energy.
The bullseye indicates actual satellite observations.
It's quite clear that only a few of the red dots are close to the observation.
The bullseye shows the satellite observations of how Earth's Energy Imbalance has changed.
Each dot represents a climate model prediction for how the earth will respond to climate change.
The models represented by yellow dots all expect small changes in the earth's climate whilst the red dots expect large changes in the earth's climate.
Considering the red dots are closer to the observations it's clear that our planet is more sensitive to the influence of air pollution than many models have been predicting.
Most of the accurate models—the ones closest to the bullseye—are shown as red dots, which are designed with high climate sensitivity.
These findings suggest that Earth is more responsive to greenhouse gases than previously assumed.
Therefore, it also suggests that aerosols have been masking this warming effect more than most scientists have been expecting.
Aerosols are expected to continue reducing in the atmosphere as many countries try to limit pollution from cars and industry.
As aerosol emissions continue to decline—due to efforts to reduce air pollution from vehicles and industry—Earth's climate may begin to reflect the full impact of greenhouse gases.
Even before this research was released NASA scientists estimated that, without aerosols, our planet could already be about 1°C hotter than it is today.
This estimate may be too low.
Wicked aerosol problem
Some argue that we should intentionally release more aerosols to cool the planet.
But this approach has serious drawbacks.
Health hazards: Aerosols—especially fine particles from smoke and industry—cause respiratory and cardiovascular diseases.
Environmental damage: Sulfur-based emissions can lead to acid rain, harming ecosystems and infrastructure.
These are just some of the reasons why many countries are reducing their emissions.
Some have suggested emitting safer types of aerosols into the air to reduce the planet's temperature – known as geoengineering.
However, this raises a series of ethical and practical dilemmas: Should humans intentionally alter the planet's climate? Could there be unintended side effects? Would such emissions need to continue indefinitely? What would happen if aerosol programs were suddenly halted? Might this approach undermine efforts to reduce COâ‚‚ emissions?
While aerosol geoengineering may one day play a role in managing climate risks, it's no substitute for cutting greenhouse gas emissions. It is, at best, a temporary patch—not a solution. Looking ahead
Humans have the technology to reduce greenhouse gas emissions, but what's lacking is political will and unified global action.
This new research suggests that climate change may accelerate more rapidly than previously feared.
As we approach—and likely surpass—the 1.5C and 2C thresholds, it's crucial to remember climate scientists claim that:
Every fraction of a degree matters.
Each additional increment of warming brings greater risk than the last.
For the latest forecasts, tune into Foxtel Channel 601 or stream on Flash.