🌡️ Climate

Background: why this matters

Climate change is unlikely to wipe out humanity directly, but it puts stress on nearly everything else on this site: food, water, health, migration and conflict. Its effects compound over decades and are hard to reverse. The physics is well established. Carbon dioxide traps heat, and burning fossil fuels has raised its concentration in the atmosphere from about 280 parts per million before the industrial era to more than 420 today, as recorded at NOAA's Mauna Loa Observatory since 1958 (the 'Keeling Curve').

The IPCC's Sixth Assessment Report concluded that human influence has unequivocally warmed the climate, and that every increment of warming raises the risk of extreme heat, heavy rain, drought and sea-level rise. Under the Paris Agreement of 2015, countries agreed to hold warming well below 2 °C above pre-industrial levels and to pursue efforts to limit it to 1.5 °C. The WMO confirmed that 2024 was the warmest year on record, about 1.55 °C above the pre-industrial average and the first calendar year above 1.5 °C. A single year above 1.5 °C doesn't break the Paris goal, which refers to long-term averages, but it shows how close that threshold is.

The scenarios that worry scientists most involve tipping points: large parts of the Earth system that could shift into a new state once pushed far enough. Examples include the loss of the Greenland and West Antarctic ice sheets, the slowdown of the Atlantic Meridional Overturning Circulation (a major ocean current system), and dieback of the Amazon rainforest. The IPCC treats these as low-likelihood, high-impact outcomes whose risk rises with warming.

This factor combines two live measurements. The first is NASA's GISTEMP global surface temperature, averaged over the latest 12 months and expressed relative to 1951–1980 (so 1.8 °C here is roughly 2 °C above pre-industrial). The second is how fast CO₂ is still rising, measured as this year's weekly Mauna Loa readings minus the same weeks a year ago. The second number matters because warming only stops once CO₂ stops accumulating. Natural cycles such as El Niño push both numbers around from year to year.

What experts watch: whether global emissions have peaked; the annual CO₂ growth rate; methane levels; ocean heat content; Arctic sea ice and ice-sheet mass loss; and signs of approaching tipping points.