Is Global Warming Speeding Up?

On Thursday, investment bank and financial services firm Jefferies published a report examining whether climate change-related warming is accelerating.

According to discussions with climate experts, Jefferies indicates that there is evidence for warming acceleration, although the extent of this varies depending on the timescales considered.

Over the past 60 years, global fossil fuel emissions have surged, increasing from approximately 22 GtCO2 per year to around 40 GtCO2 following the 2010s, thus accelerating the planet’s warming.

Natural systems, such as land and ocean carbon sinks, are absorbing a significant portion of emissions, but their efficiency seems to be declining. Currently, these systems still take in roughly 55% of emissions, yet their ability to cope with the rising atmospheric CO2 levels is diminishing.

A crucial point made in the report is the direct correlation between cumulative CO2 emissions and temperature rise, a relationship evident in Earth System Models. At present emission rates, there’s approximately a seven-year carbon budget left to restrict warming to 1.5°C, and only 28 years remaining to meet the 2°C threshold. The findings imply that urgent action is needed to limit warming.

Some scientists measure the acceleration of warming as having progressed from a rate of 0.18°C per decade between 1970 and 2010 to at least 0.27°C per decade since 2010. However, the case for acceleration appears stronger when comparing long-term periods, such as 1880-2010 versus 2011-2023.

In shorter 20-year spans, like 1970-1989 and 2004-2023, evidence of acceleration is less pronounced, highlighting that conclusions about warming trends can vary based on the chosen timeframe.

Sulfate aerosols, which historically contributed to a cooling effect by reflecting solar radiation, have been diminished due to regulatory actions aimed at curbing their adverse health effects. Experts suggest that this reduction could also play a role in the observed acceleration of warming.

With fewer aerosols present, there is less cooling, which may further contribute to warming acceleration, according to Jefferies.

The future trajectory of global warming largely hinges on how emissions are managed. Carbon removal methods, such as Direct Air Capture (DAC) and Bioenergy with Carbon Capture and Storage (BECCS), are emerging as potential strategies to mitigate future warming. However, without substantial changes in emission levels, warming and its related effects are likely to continue.

Ultimately, the report emphasizes that whether the rate of warming persists will depend on our capacity to reduce emissions. As long as emissions rise, climate change will persist, leading to increasingly severe impacts and a growing need for adaptation.