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It is not easy to keep the world’s attention for long, but three weeks of record breaking hurricanes across the North Atlantic, directly affecting multiple countries with at least 20 million people suffering one way or another, should do it. Hurricane Harvey dumped record breaking rains on Houston. Hurricane Irma decimated parts of the Caribbean and Cuba before heading through Florida to the US mainland. If that wasn’t enough hurricanes Jose and Katia followed through adding to the already devastated nations and people.
Such carnage has triggered longstanding questions about the links between hurricanes and climate. Since the mid 1970s, the number of hurricanes that reach categories 4 and 5 in strength (the two strongest classifications) has roughly doubled. With attention on the devastation in the North Atlantic, not many people realise that also in Africa and South East Asia there has been catastrophic natural disasters with enormous areas of countries becoming flooded, bringing more devastation to the world.
Although due to the nature of science climate change can’t be fully attributed to these events directly, the severity of these worldwide events and frequency are clearly increasing as our climate is changing. It is important we understand the links between climate change and natural disasters so that governments can not only mitigate against them but put into plans to better deal with them when they do happen.
There are some aspects of climate change with effects already happening that are clearly effecting natural disasters in general. Firstly, climate records are showing a clear trend towards increasing temperatures both in our oceans and atmosphere. By warming the atmosphere through greenhouse gases we’re also increasing its capacity to carry moisture, meaning more rainfall can fall at one time. This has been seen this year not only in the hurricane events in America where it looked like the rain would not stop but also across the lesser developed countries in the east where months’ worth of rain came down in a matter of hours.
Hurricanes act as heat engines that extract heat from the ocean surface and exhaust it at the upper troposphere. That means the maximum potential intensity a hurricane can attain in a given environment depends on sea surface temperature and temperature near the top of the atmospheric troposphere around 8.8 miles above the sea. In other words, a warmer sea surface temperature would result in a higher intensity storm. Under favourable conditions roughly a 1 Celsius degree increase in surface temperature leads to a 2-3% increase in hurricane strength.
This storm season we have seen sea temperatures persistently 1-2 degree Celsius above normal in the areas the hurricanes were. This translates into 3-5% more moisture in the atmosphere than normal. That large amount of moisture meant the potential for much greater rainfalls and greater flooding. Another aspect of climate change which is affecting flooding events is sea level rise.
Sea level rise attributable to climate change (some is due to coastal subsidence due to human disturbance eg oil drilling) is more than half a foot over the past few decades. This means that coastal areas (often highly populated) are at much greater danger when it comes to storms due to worsening storm surges. As storms are gaining strength they suck adjacent water into the system. This vast amount of water then gets dumped back with great intensity, high above the predicted astronomical tides. These storm surge events can increase the water level by 30 feet or more. As climate change increases the baseline sea level, these storm surges are even more deadly as coastal environments, often cities, cannot cope with such large amounts of flooding. This is even more so in countries like Bangladesh where their governments cannot afford extensive flood defences like America has.
Furthermore, at the cutting edge of climate research, scientists are exploring how climate change may affect the winds that steer hurricanes affecting storm intensity. In the case of Harvey, one of the most damaging aspects is how the system hung around in one place, thanks to weak prevailing winds. Many scientists suggest that climate change is leading to a shift of the jet stream. This could influence the steering flows that guide hurricane movement, much like a leaf carried away by a river. Variations in global circulations associated with climate change could introduce another degree of variability to hurricane impacts that we have to take into account.
It is clear that climate change is having effects on extreme weather systems. Although we cannot say that climate change created these storms, we can say that climate change made them more intense than they otherwise would have been due to higher temperatures increasing storm intensity, high sea levels increasing the severity of storm surges and a weakened weather conveyor belt which means these storms are not rushed off.
A warmer climate increases the likelihood of extremely hot days and decreases the likelihood of extremely cold days. Long term warming is also linked to more evaporation that can both exacerbate droughts and increase atmospheric moisture available to storms, leading to more severe heavy rainfall and snowfall events. However, temperature alone does not fully determine the probabilities of extreme events. Attributing specific extreme events to long term climate change may be complicated by factors such as natural long term fluctuations in the ocean surface temperatures.
Unfortunately, it is these complications in clarifying the science which governments (mainly the America one) use to put doubt on not only the effects of climate change but onto the whole idea of its existence. Mr Trump (somehow president of the US) has derided climate change as a hoax. His aids constantly declare doubt on the effects and causes of climate change. They do this because their funding comes from the industries causing climate change eg livestock industry and fossil fuel industry as the main contributors.
Miami Mayor Tomas Regalado looked beyond the suffering of the hurricanes saying it’s “an opportunity” to talk about climate change. “This is something that needs to be addressed. If Washington doesn’t want to do it, we will do it ourselves” said Mayor Regalado. The Mayor is one of a few state and local politicians in the US who intend to implement local anti-climate change measures despite Mr Trumps withdrawal from the Paris Climate Accords.
The effects of climate change are clear, and it shouldn’t take a month of devastation to put that into reality. As populations we cannot allow our governments to dumb us down on situations that are going to effect the world. It is disgusting to see how the US government are trying to put doubt in the mind of the people about climate change. As perhaps the world’s biggest super power, it should be them who are leading by example in the battle against climate change. As developed countries I believe we have a right to do something. After all it is these countries who have created the problem of climate change, and our less developed neighbours are the ones who are feeling the effects. We must not only help to mitigate the changes but help to deal with the effects of climate change.
While the global media has been glued to the action in America it is important to realise that there are many other less developed countries that have been hammered by large scale natural disasters this year. Hurricanes in the Caribbean and deadly floods across Asia and Africa have raised the issue of climate justice. We have had 30 years of well-founded scientific warnings about the relationship of climate change and the incidence and severity of extreme weather. Perhaps more problematic is the question of responsibility for climate change itself, and who should justly pay compensation for the resulting damage.
The devastation in America can and will be cleaned up. However, much of the flooding in Africa and Asia , intensified due to years of inadequate drainage systems and poor infrastructure will not be afforded the same relief. More than 1,200 people were killed in India, Bangladesh and Nepal with some 40 million more affected by the floods. More than a third of low-lying, densely populated Bangladesh, was submerged by floods. In Africa, nonstop rain and mudslides claimed over 1,400 lives in August, with the Nile water levels reaching their highest in 100 years (56 feet).
The scientific models on these areas are not all in agreement with regard to forecasts of what will happen with climate change, but the general consensus seems to be that while overall precipitation across the entire year is not likely to go either up or down significantly due to climate change, the pattern of rainfall will change significantly with greater precipitation in the monsoon season and less in the dry season.This will likely lead to more flooding in the wet season and more droughts in the dry season.
In conclusion, while we cannot say climate change “caused” these events to happen, we can say that it exacerbated several characteristics of all the events in a way that greatly increased the risk of damage and loss of life. Obama’s presidential adviser John Holdren put the challenge of climate change bluntly: We will end up with some mix of prevention, adaptation and suffering; it is for us to determine the ratio. It is not only in the hands of our governments to halt climate change, it is in our hands. By making climate change an everyday discussion, by changing the way we live our everyday lives to alleviate our input to climate change whether that by using our car less or cutting out meat from our diets. The important thing is to have your voice heard, and not let large corporations and governments slowly destroy the planet we live on.
