18. What are scientists doing to address key uncertainties in our understanding of the climate system?

Science is a continual process of observation, understanding, modelling, testing and prediction. The prediction of a long-term trend in global warming from increasing greenhouse gases is robust and has been confirmed by a growing body of evidence. Nevertheless, understanding (for example, of cloud dynamics, and of climate variations on centennial and decadal timescales and on regional-to-local spatial scales) remains incomplete. All of these are areas of active research.

Comparisons of model predictions with observations identify what is well-understood and, at the same time, reveal uncertainties or gaps in our understanding. This helps to set priorities for new research. Vigilant monitoring of the entire climate system—the atmosphere, oceans, land, and ice—is therefore critical, as the climate system may be full of surprises.

Together, field and laboratory data and theoretical understanding are used to advance models of Earth’s climate system and to improve representation of key processes in them, especially those associated with clouds, aerosols, and transport of heat into the oceans. This is critical for accurately simulating climate change and associated changes in severe weather, especially at the regional and local scales important for policy decisions.

Simulating how clouds will change with warming and in turn may themselves affect warming, remains one of the major challenges for global climate models, in part because many cloud processes occur on scales smaller than the current models can resolve. Greater computer power may enable some of these processes to be resolved in future-generation models.

Dozens of groups and research institutions work on climate models, and scientists are now able to analyse results from essentially all of the world’s major Earth-System Models and compare them with each other and with observations. Such opportunities are of tremendous benefit in bringing out the strengths and weaknesses of various models and diagnosing the causes of differences among models, so that research can focus on the relevant processes. The differences among models allow estimates to be made of the uncertainties in projections of future climate change, and in understanding which aspects of these projections are robust.

Studying how climate responded to major changes in the past is another way of checking that we understand how different processes work and that models are capable of performing under a wide range of conditions.

Questions and answers

Read short summary answers

1. Is the climate warming?
2. How do scientists know that recent climate change is largely caused by human activities?
3. CO2 is already in the atmosphere naturally, so why are emissions from human activity significant?
4. What role has the Sun played in climate change in recent decades?
5. What do changes in the vertical structure of atmospheric temperature – from the surface up to the stratosphere - tell us about the causes of recent climate change?
6. Climate is always changing. Why is climate change of concern now?
7. Is the current level of atmospheric CO2 concentration unprecedented in Earth’s history?
8. Is there a point at which adding more CO2 will not cause further warming?
9. Does the rate of warming vary from one decade to another?
10. Does the recent slowdown of warming mean that climate change is no longer happening?
11. If the world is warming, why are some winters and summers still very cold?
12. Why is Arctic sea ice reducing while Antarctic sea ice is not?
13. How does climate change affect the strength and frequency of floods, droughts, hurricanes and tornadoes?
14. How fast is sea level rising?
15. What is ocean acidification and why does it matter?
16. How confident are scientists that Earth will warm further over the coming century?
17. Are climate changes of a few degrees a cause for concern?
18. What are scientists doing to address key uncertainties in our understanding of the climate system?
19. Are disaster scenarios about tipping points like ‘turning off the Gulf Stream’ and release of methane from the Arctic a cause for concern?
20. If emissions of greenhouse gases were stopped, would the climate return to the conditions of 200 years ago?

Your questions

In addition to the 20 key questions answered in 'Climate Change: Evidence & Causes', we asked for your questions about the science of climate change on Google Moderator.

View all questions and our responses.

Download the answers (PDF).