Quote:

. . .We conclude that 2024 was the warmest year on Earth since 1850, exceeding the previous record just set in 2023 by a clear and definitive margin. This period, since 1850, is the time when sufficient direct measurements from thermometers exist to create a purely instrumental estimate of changes in global mean temperature. The last ten years have included all ten of the warmest years observed in the instrumental record. The warming spike observed in 2023 and 2024 has been extreme and represents a larger than expected deviation from the previous warming trend. The spike has multiple causes, including both natural variability and man-made global warming from the accumulation of greenhouses gases; however, as discussed below, we believe additional factors are needed to explain the full magnitude of this event. Reductions in low cloud cover and man-made sulfur aerosol pollution are likely to have played a significant additional role in recent warming. Over the previous 50 years, global warming has preceded in an almost linear fashion, consistent with an almost linear increase in the total greenhouse gas forcing. The warming spike in 2023/2024 suggests that the past warming rate is no longer a reliable predictor of the future, and additional factors have created conditions for faster warming, at least in the short-term.

“. . .past [linear] warming rate” is no longer a guide to predicting how temperatures will increase.

That is actually quite frightening.

Where should you live to avoid the worst of extreme temperatures? How should you live? An underground house? Earth sheltered house?

How will climate have changed in 10 years, 20? Besides the at least formerly linear increase in surface temperatures what other changes will there be to climate, like rainfall? You can’t change one climate factor without others changing as a result.

Quote:

The global annual average for 2024 in our dataset is estimated as 1.62 ± 0.06 °C (2.91 ± 0.11 °F) above the average during the period 1850 to 1900, which is traditionally used a reference for the pre-industrial period. This is first time Berkeley Earth has reported an annual average above 1.6 °C (2.9 °F), and the only second time that Berkeley Earth has reported any year exceeding the key 1.5 °C (2.7 °F) threshold, after slightly doing so in 2023. Due to uncertainties and differences in methodologies, other groups are expected to report 2024 as slightly cooler. The ECMWF’s Copernicus research service joins us in just barely exceeding 1.6 °C (2.9 °F), while other groups are somewhat cooler. The differences between Berkeley Earth’s analysis and that of other groups is discussed at the end of this report. A goal of keeping global warming to no more than 1.5 °C (2.7 °F) above pre-industrial has been an intense focus of international attention. This goal is defined based on multi-decadal averages, and so a single year above 1.5 °C (2.7 °F) does not directly constitute a failure. However, recent warming trends and the lack of adequate mitigation measures make it clear that the 1.5 °C goal will not be met. The long-term average of global temperature is likely to effectively cross the 1.5 °C (2.7 °F) threshold in the next 5-10 years. While the 1.5 °C goal will not be met, urgent action is still needed to limit man-made climate change. Each increment of additional warming, e.g. 1.6 °C, 1.7 °C, etc., will lead to additional and compounding climate change impacts that can still be avoided if effective mitigation steps are made to reduce man-made greenhouse gas emissions.

“additional and compounding climate change impacts”

That is the kicker!

—Prevailing wind direction and strength (and that in itself will affect other climate factors, compounding, see?

—Rainfall

—Nature and length of the seasons. Think this might impact farming?

—Stream flows affected by a combination of changed rainfall and increased evaporation due higher temperatures.

—Bushfire season, length and severity

One example of changes to weather and climate besides >1.5°C temperature increase:


Quote:

MECCA FLOODS: Torrential, unseasonal rain lashed cities in Saudi Arabia on Wednesday, with the holy city of Mecca facing the “worst floods”, Down to Earth reported.

—Carbon Brief.

This is not the only indicator of rain in the Arabian desert.

https://berkeleyearth.org/wp-content/uploads/2025/01/2024-Global-Time-Series-1024x564.png

Quote:

In Berkeley Earth’s analysis the global mean temperature in 2023 is estimated to have been 1.62 ± 0.06 °C (2.91 ± 0.11 °F) above the average temperature from 1850-1900, a period often used as a pre-industrial baseline for global temperature targets. This is ~0.08 °C (~0.14 °F) warmer than the previous record high observed in 2023. As a result, 2024 is the warmest year to have been directly observed using thermometer measurements, and stands out well-above all previous years. Though the availability of thermometers limits direct measurements to the period since 1850, indirect evidence suggests that the Earth is currently at its warmest global average temperature for at least several thousand of years, and possibly the warmest since the last interglacial ~120,000 years ago. The abrupt increase in temperatures from 2022 to 2024 is the largest two year increase since the 1870s. This is the second time in Berkeley Earth’s analysis that an annual average temperature has exceeded the pre-industrial baseline period by more than 1.5 °C (2.7 °F), having previously done so by a small margin in 2023. It is the first time that an annual average has exceeded 1.6 °C (2.9 °F) in our analysis. As discussed at the end of this report, other research groups have slightly different estimates, some of which also cross these thresholds and others are slightly cooler. Under the Paris Agreement, many countries have set an aspirational goal of limiting long-term global warming to no more than 1.5 °C (2.7 °F). That target is based on the state of the climate averaged over many years, so it is not automatically considered to have been breached by one or two years exceeding 1.5 °C of warming. However, it is clear that this 1.5 °C (2.7 °F) threshold is no longer avoidable and the long-term average of global warming will likely cross this threshold in the next 5-10 years. Urgent efforts to reduce greenhouse gas emissions would be needed to avoid even higher levels of warming, and the potential for even greater negative impacts. Every increment of warming will matter, so even after 1.5 °C is passed, continued efforts to avoid 1.6 °C, 1.7 °C, etc., will still be needed. The last ten years stand out as the ten warmest years to have been directly observed.[My emphasis.

Quote:

[Are these changes faster than expected? Since 1970, global warming has proceeded at a roughly linear pace. This roughly linear pace has been consistent in both rate and magnitude with the expected effects of increasing greenhouse gases during this period. However, the warming spike in 2023/2024 appears to have deviated significantly from the previous trend. If we were to assume that global warming was continuing at the same rate as during the 50-year period 1970-2019, then the 2023/2024 excursion would be by far the largest deviation from that trend, with only a roughly 1-in-100 chance of occurring solely due to natural variability.

https://berkeleyearth.org/wp-content/uploads/2025/01/Expect-GHG-Warming-1024x564.png

Quote:

However, the warming spike in 2023/2024 appears to have deviated significantly from the previous trend. If we were to assume that global warming was continuing at the same rate as during the 50-year period 1970-2019, then the 2023/2024 excursion would be by far the largest deviation from that trend, with only a roughly 1-in-100 chance of occurring solely due to natural variability.

https://berkeleyearth.org/wp-content/uploads/2025/01/Exceptional-Warming-1024x564.png

Note how the lows are not as far below the trend line as the highs are above it. Low temperatures are increasing faster than high temperatures especially this century.

Pt 2 completed. More parts to come.