The role of different timescales
What is the difference between a weather forecast and a climate projection?
A weather forecast provides an assessment of the weather over the next few days for a given area. A climate projection aims to provide an indication of the weather and weather extremes associated with a particular future climate over decades to centuries into the future.
Vitally, a climate projection does not attempt to forecast the weather on each day for decades ahead – that is impossible. Instead, it provides a guide to the climate and extreme weather events that are plausible in the future.
As an example, using a weather forecast a farmer might be able to make an assessment of whether the weather conditions are favourable to harvest a crop. But, using a climate projection, the same farmer will have an insight into future decisions. These might include what crops to grow in 30 years’ time, or whether there is a need to build an on-farm reservoir or plant more shade trees to cope with future changes in climate.
Climate projections show a spread of possible outcomes, and this is useful to assess opportunity or risk. In the UK, climate projections show a tendency towards warmer and wetter winters, and hotter and drier summers.
Natural variability in the weather will continue to play a huge role in year-to-year variation. We cannot know whether the summer of 2050 is likely to be extremely hot. But based on climate projections, we know that it is likely to be warmer than the average we expect to see now and there is a strong chance that it may exceed the extremes we have already seen.
A climate projection will take account of factors like increasing quantities of greenhouse gases, rising sea levels or reduced amounts of sea ice at the poles. By contrast, a weather forecast includes much finer detail, factoring in all of the current world’s weather to assess how the conditions of yesterday and today will affect the world tomorrow and over the coming week.
The misinformation you may encounter
- Climate predictions shouldn’t be believed as you can't even get a forecast accurate hour by hour.
Our response: Weather forecasts and climate projections are very different things. They have different goals and work in such different ways that one should not be used to comment on or disparage the other.
We are consistently in the top two weather forecasting centres in the world for accuracy. 92.5% of the Met Office’s next day temperature forecasts are accurate within 2 °C and 92% of the Met Office’s next day wind speed forecasts are correct within five knots. You can learn more on our accuracy webpage.
Climate projections have proven accurate over time, even quite old ones. One study looked at 17 climate projections from between 1970 and 2007 and found their predictions of surface temperatures were remarkably accurate. Climate scientists continue improving their models, building upon this success.
- You make 2050 forecasts, but then say you can't forecast for 25 years’ time; how does that work?
Our response: Our 2050 forecast videos are based on a set of climate projections to highlight plausible weather in the UK and around the world in a future climate. We cannot know what the exact weather will be like in summer 2050 because there is variability within the weather. But the projections show an increasing tendency towards hotter and drier summers. The 2050 forecast videos make it clear that they are representative of what a forecast might look like in 2050 given what we know from our climate projections, rather than cast-iron forecasts of what will happen.
- Previous climate projections haven’t come true.
Our response: Even climate models from over 40 years ago made accurate predictions about future warming. Now that enough time has passed, we can compare those projections with observations of what we see today. Scientists looked at 17 global surface temperature projections from studies between 1970 and 2007 (Hausfather et al. 2019), to see how accurate they were. They found temperatures were “pretty much right on where models have predicted” (Science).
We are always improving our climate models, which build upon this success, and continue to make finer-resolution projections.