Capital

Climate Change Controversies

(continued from last week)

Misleading argument 7: 'the climate is actually affected by cosmic rays'
"The climate is actually affected by cosmic rays."
What does the science say?
Any effect that cosmic rays could have on the climate is not yet very well understood but, if there is one, it is likely to be small. Cosmic rays are fast moving particles which come from space, and release electric charge in the atmosphere.
Experiments done in a laboratory hint that cosmic rays could play a role in the development of tiny particles that could in turn play a part in the formation of clouds. If this happens in the same way in the atmosphere - which isn't proven - it might lead to more clouds, which generally have a cooling effect by reflecting the Sun's rays back into space. Whether the whole chain of processes actually occurs in the atmosphere is speculative, but some of the individual steps are plausible.
It has been proposed that this process would act to enhance the influences of the Sun on the climate. We know that when the Sun is more active its magnetic field is stronger and this deflects cosmic rays away from the Earth. So the argument is that a more active Sun would lead to fewer cosmic rays reaching the Earth, resulting in fewer clouds and therefore a warmer Earth.
However, observations of clouds and galactic cosmic rays show that, at most, the possible link between cosmic rays and clouds only produces a small effect. Even if cosmic rays were shown to have a more substantial impact, the level of solar activity has changed so little over the last few decades.The process could not explain the recent rises in temperature that we have seen.
Misleading argument 8: 'the negative effects of climate change are overstated'
"The scale of the negative effects of climate change is often overstated and there is no need for urgent action."
What does the science say?
Under one of its mid-range estimates, the Intergovernmental Panel on Climate Change (IPCC) - the world's leading authority on climate change - has projected a global average temperature increase this century of 2 to 3 ºC. This would mean that the Earth will experience a larger climate change than it has experienced for at least 10,000 years. The impact and pace of this change would be difficult for many people and ecosystems to adapt to.
In the short term, some parts of the world could initially benefit from climate change. For example, more northerly regions of the world may experience longer growing seasons for crops and crop yields may increase because increased levels of carbon dioxide in the atmosphere would have a fertilizing effect on plants.
However the IPCC has pointed out that as climate change progresses it is likely that negative effects would begin to dominate almost everywhere. Increasing temperatures are likely, for example, to increase the frequency and severity of weather events such as heat waves, storms and flooding.
Furthermore there are real concerns that, in the long term, rising levels of greenhouse gases in the atmosphere could set in motion, large-scale and potentially abrupt changes, in our planet's natural systems and some of these could be irreversible. Increasing temperatures could, for example, lead to the melting of large ice sheets with major consequences for low lying areas throughout the world.
And the impacts of climate change will fall disproportionately upon developing countries and the poor those who can least afford to adapt. Thus a changing climate will exacerbate inequalities in, for example, health and access to adequate food and clean water.