Weather extremes and catastrophic climate change

Extreme weather events such as heat waves, storms and floods are now frequently on the news, raising the question: Is this related to climate change? Attributing a single weather event to climate change is difficult because of natural variations in climate and the fact the these events are often caused by a combination of factors. However, some extreme weather events have become more likely and been recorded more frequently since c. 1950. These include heat waves and heavy precipiation events. Both are the consequence of higher global average temperatures. As a warmer atmosphere can hold more moisture, heavier rainfall events become more likely. Attributing a storm to climate change is more difficult because of uncertainties associated with historical records due to technological changes and the complexities of the physical mechanims involved. However, there is evidence that the number of the strongest tropical cyclones has increased in the North Atlantic since the 1970s (start of satellite records).

It is storms that currently make the headlines. In August, Hurricane Harey made landfall in Texas and broke the precipiation record for a single weather event in the United States. A few days ago, Hurricane Irma first hit the Caribbean as one of the strongest storms in the Atlantic before continuing along the west coast of Florida. Both storms flooded vast areas and the water and winds damaged buildings and public infrastructure. Anthropogenic climate change has made the occurrence of these storms more likely but talking about a connection is being avoided by the Trump administration and other officials. But these catastrophic storms certainly won’t have been the last.

While storms and other extreme weather events can certainly have catastrophic impacts, I don’t think the word catastrophic should be used in connection with climate change. The fourth assessment report from the IPCC states: “The possibility of abrupt climate change and/or abrupt changes in the earth system triggered by climate change, with potentially catastrophic consequences, cannot be ruled out.” But the word “abrupt” refers to long-term changes that happen over decades to centuries, not days like a hurricane. If we think of climate change as a future event with catastrophic consequences, we might perceive it as a threat. In case of an approaching hurricane, feeling fear makes us protect ourselves and save our life. But in case of climate change, a sense of anxiety might make us view pessimisticly into the future. The global scale of climate change and uncertainties associated with future projections certainly don’t help us to respond.

Climate change is already happening and it is going to continue to happen even if we ceased the emission of greenhouse gases today.  For us, climate is not going to change abruptly but gradually. Now it is up to us to decide whether we want to continue as before or change to limit future changes in climate.

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