Late last week Hurricane Irma - the biggest storm ever recorded in the mid-Atlantic - tore through the Caribbean on its way to the exposed coast of Florida. The megastorm headed towards continental United States as Texans were still counting the cost of Hurricane Harvey.

Climate scientists were startled by the two destructive storms occurring so close together and speculated whether they were a worrying sign of a "new normal" in which extreme weather events become more intense as a result of man-made climate change.

What is indisputable is the physics: the storms packed punch because water surface temperatures in the region are high. Hurricanes draw energy and moisture from ocean heat. What is less clear is the extent to which rising greenhouse gas emissions are driving the extreme weather. What the scientists agree on is the need to urgent action for governments to reduce emissions and prepare for a warmer future and more disasters.

US experts have produced a report which the White House is sitting on. It concludes that evidence for climate change abounds, "from the top of the atmosphere to the depths of the ocean".


The study reports that it is possible to attribute some extreme weather to climate change through the work of experts in the field known as "attribution science" which itself has advanced rapidly in response to events such as heat waves, intense rainstorms and coral reef destruction.

This runs counter to claims by the Trump administration which take the view that the human contribution to climate change is uncertain, and that the ability to predict the effects is limited.

In a striking parallel a New Zealand report has emerged in similar circumstances. The Ministry for the Environment risk assessment was completed in April and only saw the light of day because it was given to the Green Party which promptly made it public. The report, though still in draft form, is intended to guide local government managers with their coastal hazard planning. Its contents ought to set off alarm bells about whether climate change is being addressed here with sufficient urgency.

The report calculates there are more than $19 billion worth of buildings at-risk nationwide from sea level rise, in areas where 130,000 people live. Big cities and small communities in low lying areas face large potential bills. The smaller centres have little prospect of meeting the cost. Whakatane has $500 million of at-risk assets, Dargaville $120m, Gisborne $75m. On the Hauraki Plains, the settlement of Ngatea has assets worth $75m just 50cm above the mean high water spring mark. Overall, five airports and 2000km of roads could be affected by rising sea levels, which underlines the disruption transport faces.

The country's mayors, who know their towns will be in the firing line, have urged the Government to grasp the nettle and act sooner, not later.

Climate change has been a sleeper this election with the economy, tax and inequality front and centre. When the dust settles after September 23 the issue needs to get some serious attention.