1880-2020 Trends in Ocean Heat Uptake, Thermal Expansion Challenge Human Forcing Claims

A scenic view of the ocean with sunlight reflecting on the water's surface and dramatic clouds in the sky.

From No Trick Zone

By Kenneth Richard

Fundamental assumptions in projections of alarming, CO2-induced global warming in the coming decades are undermined by a new long-term energy budget analysis.

In a new study scientists have acknowledged the modeled assumptions forecasting nature’s response to the presumed human-driven radiative forcing of ocean heat uptake, thermal expansion, and sea level rise rates do not align well with observations from recent decades.

A diagram illustrating the global ocean heat uptake rate from 1880 to 2020, featuring multiple graphs representing various studies on effective radiative forcing and Earth's radiative response.
Image Source: Wu et al., 2025

The apparent misalignment is especially pronounced during 2000-2020 (Fig. 2 in the image), as the assumed uptick in radiative forcing (which is said to be a consequence of rising human CO2 emissions) was not accompanied by a sharp increase in Earth’s energy imbalance (EEI). Instead, the assumed forcing values are 50% greater than EEI estimates during this period.

When the entire 1880-2020 period is considered, it is notable that the fraction of forcing that delivers heat energy to the Earth has been (much) smaller in recent decades than in the first half of the 20th century despite the assumed cause of the forcing (human CO2 emissions) being several times larger since about 1980.

Consider that from 1910 to 1945 human CO2 emissions remained relatively flat at ~1 GtC/year, but then emissions rose to ~6 GtC/year by 1990 and to nearly 10 GtC/year by the 2010s. Despite this dramatic increase in the assumed radiative forcing from CO2 emissions, the heat uptake (Fig. 1 and S6), thermal expansion (Fig. S17), and sea level rise rates (Fig. S17) were nearly as pronounced in 1910-1945 as they were from 1980-2010. In fact, there was a decline in the heat uptake, thermal expansion, and sea level rise rates from 1945 to 1975 despite the coincident sharp increase in CO2 emissions during this period.

“We find two distinct phases in the global energy budget. In 1880–1980, Earth’s energy imbalance closely followed the radiative forcing. After 1980, however, Earth’s energy imbalance increased at a slower rate than the forcing; in 2000–2020, the imbalance amounted to less than 50% of the forcing.”

Since nearly all projections of catastrophic global warming, ocean heat uptake, and thermal-expansion-driven sea level rise are rooted in the presupposition that dramatic increases in radiative forcing from rising CO2 emissions will lead to pronounced increases in the EEI, scientists are now indicating we may not sufficiently understand these processes and thus we need to consider further study.

“Because the global energy budget before and after 1980 implies very different global warming in the future, further studies are required to better understand the cause of this historical variation.”

Graph depicting the global energy budget and ocean heat uptake rates from 1880 to 2020, illustrating sea-level rise contributions from thermal expansion and ocean mass change.
Image Source: Wu et al., 2025


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