Quarterly Global Warming Report

Each blue, yellow, and red circle represents the average global air temperature in a prior month between 1960 and 2022, black circles represent data for 2023, and black squares represent data for 2024. From June 2023 through March 2024, global air temperature has been at record-high levels.

It is worthwhile to briefly explain the seasonal cycle of global average temperature that is apparent in this graph. The seasonality may seem counterintuitive given that, on a global level, the earth receives about the same total amount of solar energy per day throughout the year. When the northern hemisphere experiences fall and winter, the southern hemisphere experiences spring and summer, and vice versa. Less daylight in one hemisphere is counterbalanced by more daylight in the opposing hemisphere. This suggests that the global average temperature should remain roughly constant from one month to the next. However, the northern hemisphere contains over two-thirds of the earth’s land mass, and, in general, land heats up more quickly than does water in response to a given influx of solar energy. Consequently, global average temperature carries a strong signature of the northern hemisphere’s seasonal temperature changes.

Across the most recent 12 months of data -- from April 2023 through March of 2024 -- the average global air temperature was 59.13F, which is a record-high measurement across a 12-month period, and is 1.76F greater than the 1960-to-2019 average of 57.37F.

In the parlance of climate scientists, temperatures defined relative to their corresponding long-term averages are termed “temperature anomalies”. This graph presents both air temperature and sea-surface temperature anomalies. Each anomaly is defined as temperature averaged across a 12-month period minus the long-run average temperature computed across 1960 to 2019. Like the preceding graphs, this graph plots data through March of 2024. The anomalies on the far-right of the graph are computed across the 12-month period from April 2023 to March 2024, and are at record-high levels.

This graph resembles the preceding graph, but the anomalies are averaged across the trailing 60 months rather than 12 months. The longer averaging period provides a better view of long-term trends. In addition to global temperature computed across the entire surface of the earth, the graph shows air temperature averaged across all land areas and air temperature averaged across all oceans and other bodies of water. The results reveal that air temperature over land has risen at a significantly faster rate than air temperature over oceans, which, in turn, has risen at a faster rate than sea-surface temperature.

While global warming rates can change across time, it is nevertheless useful to fit a linear regression to the data, thereby producing an estimated rate-of-warming that is constant across time. Regressions were run across two overlapping time periods: (1) 1960 to 2024 and (2) 2000 to 2024. The graph presents the best estimates for warming trends. “Air, Land” is air temperature averaged across all land areas, while “Air, Land N” and “Air, Land S” capture solely the land areas in the northern and southern hemispheres, respectively. “Air, Ocean” is air temperature across all bodies of water. “Sea surface” is the average water temperature across the surface of oceans and other bodies of water.

The regression results reveal the following:

• Global average air temperature over land is increasing at about twice the rate of air temperature over oceans, and at nearly three times the rate of sea-surface temperature.
• Average air temperature over land is increasing at a significantly faster rate in the northern hemisphere compared to the southern hemisphere.
• Warming rates estimated across the 2000-to-2024 period are significantly greater than those estimated across the 1960-2024 period, perhaps suggesting an acceleration of global warming.