According to the National Oceanic and Atmospheric Administration, the Atlantic hurricane season started on June 1. But nature — especially when juiced by extra carbon dioxide in the atmosphere — doesn’t always play by our rules. This year, Tropical Storm Ana was 2021’s season opener, giving the Atlantic its first named storm on May 14.
Each of the last six years has spawned a named storm in May. There are also trends toward tropical systems intensifying more rapidly, trends in the number of powerful Category 4 and 5 hurricanes, and trends in the amount of rain and total energy delivered to the earth’s surface by tropical cyclones — a term that applies to tropical storms, hurricanes and typhoons, depending on where they are.
Physics suggests that there should be a link between stronger, wetter and earlier tropical cyclones and climate change. Tropical cyclones get their energy and moisture from warm ocean waters. Ocean temperatures are rising, and ocean warming has been conclusively linked to climate change.
To really show a connection, we would like to see the physical arguments supported by strong signals in the data. Comprehensive data on tropical cyclones only became available in the late 1960s with the launch of the first weather satellites, which allow scientists to see storms that never touch land.
A recent expert assessment in the Bulletin of the American Meteorological Society (BAMS) suggests that it may take 60 years of data to see a conclusive signal that climate change is behind the tropical cyclone trends. This means that we may have to wait another decade — and face many more storms — before we reach rigorous scientific certainty.
This timeline problem is baked into the very nature of climate change and science. By design, science is a conservative process that sets a high bar on saying that something novel — in this case, that climate change drives tropical cyclone trends — is true. This conservatism is useful for building our knowledge of how nature works, but too often, our lack of certainty has been used as an excuse for inaction. The more we wait, the more evidence accumulates, and the clearer the links become. For hurricanes, the waiting game means we might know in 2031 that we should have started preparing in 2021 for worse storms.
Waiting for scientific certainty before planning for stronger storms comes with costs, a point that was emphasized in the BAMS report. Presuming that there is no link between the storm trends and climate change means implicitly assuming that our current coastal infrastructure and policies like flood insurance will work just as well in the future as they do today. It means exposing people, communities, and economies to escalating risk and losses rather than taking action to mitigate those risks.
And science is clear about escalating risks and losses. In addition to providing more energy for storms, a warmer ocean also expands to take up more space, leading to rising sea levels. Many places in the path of Atlantic hurricanes have already experienced 8 inches of sea-level rise since 1960. Although climate change might not have made 2012’s Hurricane Sandy more powerful, rising seas added at least $8 billion to the damages from this storm.
A colleague recently commented that “there is no such thing as a natural disaster.” Their point was that nature provides the storms, but our choices, both individually and as a society, determine how big of a disaster we experience.
While it might not have reached the level of certainty that science aspires to, there is ample and growing evidence that carbon pollution has made hurricanes more powerful and damaging — and that future storms can be expected to be even more powerful and more damaging. We shouldn’t wait to protect ourselves. It is time to begin incorporating that knowledge into our planning in order to reduce the impact of future storms on our economy and communities.
Andrew Pershing is the director of Climate Science at Climate Central. He is an expert on how climate trends and events impact ecosystems and people and recently led the Oceans and Marine Resources chapter of the 4th U.S. National Climate Assessment. Follow him on Twitter: @Sci_Officer.