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The climate varies on multiple timescales, but now humans are the main agents of change and are likely to remain so for the next few centuries. It is generally understood that human-induced climate change causes global warming, but what is not adequately appreciated are the direct influences on heavy rainfalls, drought and storms, at great cost to society and the environment. Although the climate change effects are modest, perhaps five to 15 per cent for these events, once thresholds are crossed, things break and damage increases non-linearly. These aspects are not properly factored into costs of climate change, and preparation for expected effects is woefully inadequate, exacerbating damage.
Keywords: climate change; extreme weather; mitigation; adaptation; global warming
1.Introduction
There are many facts related to climate (see below) to demonstrate conclusively that the problem of human-induced climate change is real. The observational evidence combined with physical understanding based on well-established physical principles makes this abundantly clear. Former United States Senator Patrick Daniel Moynihan famously said 'Everyone is entitled to his own opinion, but not his own facts.' The observations and data - the facts - are of mixed quality and duration, but together tell a compelling story that leaves no doubt about the human role in climate change. Changes in some phenomena, such as hurricanes and tornadoes, are confounded by the way observations are made (eg, the role of satellites) and shortness of reliable records. But the absence of evidence is not evidence of absence of important changes, and our physical understanding and climate modelling can fill the gaps. However, the facts are not enough. The role of scientists is to lay out the facts, evidence, prospects and consequences, but the decisions on what to do about them reside in the realm of politics and should involve all of society.
The Intergovernmental Panel on Climate Change (IPCC),1 US national assessments,2 reports from the National Academy of Sciences3 and many other scientific organisations have proclaimed that 'global warming is unequivocal' and it is mainly caused by human activities. Yet the public is not alarmed. Many politicians either do not believe in global warming or discount it. But it is not a matter of belief. From the scientific standpoint, by the time the problems associated with climate...