In December, world leaders made an unprecedented agreement to limit human-caused global warming to 2C, with a "reach" goal of 1.5C. The Paris agreement hasn't even been formally signed, and now, it's looking like our planet might close in on that reach goal by 2017. Over the past year, the world has smashed so many temperature records that we've grown desensitised — March 2016 marked the 11th consecutive month where global average temperatures hit an all-time high. As I've discussed before, there are a number of different factors playing into our planetary hot flash, including the 2015 monster El Niño and changes to the distribution of heat in the Pacific Ocean. Underlying it all is a general warming trend caused by humans dumping some 40 billion tonnes of carbon dioxide into the air every year.
— Gavin Schmidt (@ClimateOfGavin) April 15, 2016
Carbon dioxide is the climate master dial that we need to crank down, and we're not doing it yet. On Earth Day this week, more than 150 governments are expected to attend a symbolic signing of the Paris climate agreement. But the initial target date for beginning our global carbon diet was 2020. Before we even start, it's looking like we might hit the very warming milestone many hoped we'd stay below.
On Twitter this week, Gavin Schmidt, head of NASA's Goddard Institute for Space Studies, estimated that the global average temperature in 2016 could land anywhere between 1.1 and just shy of 1.5C above the long-term average. There's still a great deal of uncertainty in this estimate. But what is clear is that we're edging dangerously close to a big target. What's more, it's very possible our global thermostat will temporarily rise 1.5C above pre-industrial levels this winter. (It almost did in February.)
Of course, a milestone is just a milestone. But 1.5C is an important one. It's a milestone that island nations like the Maldives and Kiribati, which are already going underwater, fought long and hard to keep in the text of the Paris agreement. It's a milestone marine biologists say we need to adhere to if we want to keep the Great Barrier Reef alive.
Let's just hope that as world leaders get together this week to discuss climate for the first time since Paris, we can find a way to ratchet up the ambition even further.