Hurricane Matthew & climate change: what you need to know​

A highly destructive and deadly hurricane has torn through Haiti, tragically claiming hundreds of lives, and is now en route to make landfall in the southeastern United States.

The massive size of this hurricane has prompted many in the public and the media to question the influence of climate change on extreme weather events such as hurricanes (also known as tropical cyclones in Australia and typhoons in east Asia).

In a nutshell: climate change is making extreme weather events like Hurricane Matthew worse.

We break down the link between the two below.

What do we know so far about Hurricane Matthew?

  • It’s highly destructive. Hurricane Matthew was a Category 4-5 cyclone for 102 hours, which is the longest time a Hurricane of such high intensity has been sustained in eastern Caribbean history. This build-time increases the Hurricane’s energy and its destructive capacity.
  • It’s killed at least 260 people already. Hurricane Matthew has already caused severe damage across the Caribbean, including Haiti which has been most affected, killing at least 260 people there, damaging 28,000 homes with 350,000 people requiring assistance following the disaster.
  • It’s now on a direct path to Florida. Now Hurricane Matthew is on a direct path towards Florida and is expected to make landfall by Friday the 7th of October 2016 at 5pm AEST. Over 2 million people have been urged to evacuate their homes in coastal regions of Florida, Georgia and South Carolina.
  • Life-threatening winds and rainfall. Up to 210 kph winds and a storm surge of up to 3.3 m is expected along the coast from central Florida to Georgia. Projections show rainfall of 130 to 250 mm with life-threatening inundation over the next 36 hours.
  • Large-scale blackouts. The hurricane has already left tens of thousands of customers in Florida without power, but is expected to have 2.5 million statewide outages after the storm hits.

What's the impact of climate change on hurricanes?

Higher seas and more damaging coastal flooding

  • Climate change is increasing sea levels, exacerbating the destruction of storm surges that accompany hurricanes/tropical cyclones.
  • The most direct influence of climate change on the impacts of hurricanes/tropical cyclones is via coastal flooding.
  • Global sea level has already risen by about 20 cm since the mid-19th century and continues to rise, with a projected additional rise of 40 cm to nearly 1m by 2100 compared to 1990 levels.
  • Higher sea level means that storm surges (a rise above the normal sea level resulting from strong onshore winds and/or reduced atmospheric pressure as a result of storm activity) are occurring on a higher base sea level and are causing more extensive flooding of coastal areas.
  • Typically the damage from hurricanes/tropical cyclones comes from the excessively high winds that directly damage built infrastructure and the natural environment, as well as the extensive flooding of coastal regions that occurs from a storm surge and heavy rainfall that often accompanies the hurricane.
  • In the case of Hurricane Matthew, oceans in the subtropics to the southeast of the US have warmed significantly as a result of climate change. This has very likely contributed to rapid intensification of Hurricane Matthew.

Stronger storms and more intense rainfall

  • The increasingly warmer ocean temperatures that come with a changing climate are also affecting the intensity of cyclones because the storms draw energy from the surface waters of the ocean. This can increase wind speed and trigger more intense rainfall. It is virtually certain that there has been an increase in intense tropical cyclone activity in the North Atlantic since 1970.

TL;DR? Here's a handy explainer from 350.org:

What does all this mean for Australia?

Australia is highly vulnerable to increasing coastal flooding that can accompany severe storms and cyclones because our cities, towns and critical infrastructure are mainly located on the coast. Australia’s infrastructure has been built for the climate of the 20th century and is unprepared for rising sea level and more intense storms.

In Australia, 1.1 metres of sea level rise puts more than $226 billion worth of critical infrastructure, including $87 billion worth of commercial and light industrial buildings, $72 billion worth of homes and $67 billion worth of road and rail at risk from coastal flooding and erosion. Read more in our report, Counting the Costs: Climate Change and Coastal Flooding.

What can we do?

We need deep and urgent cuts in greenhouse gas emissions this decade and beyond if we are to avoid the most dangerous impacts of rising sea levels, coastal flooding and more intense storms.

Australia is one of the largest emitters to delay ratification of the United Nations Paris agreement. It’s time for Australia to ratify the Paris agreement and turn aspiration into action before the next extreme weather event hits.


References

ABC News: Hurricane Matthew: Millions Warned That ‘This Storm Will Kill You’

National Oceanic and Atmospheric Administration: Hurricane MATTHEW Public Advisory

The Weather Channel: Thousand Without Power in Florida as Hurricane Matthew Begins Its Assault

The Weather Channel: Hurricane Matthew Kills at Least 264 in Haiti: The Situation is Catastrophic.

The Washington Post: It not hype: Hurricane Matthew has been blasting through records

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