Ditching the 2 Degree Climate Goal?

It's time to ditch the climate goal of limiting global warming to 2 degrees Celsius (3.6 degrees Fahrenheit), a pair of Californian scientists argued in an essay released this week. It's an opinion that's likely to spark a lot of heated debate in the climate science community.

This theoretical line in the sand was drawn in 2009 at the United Nations (UN) Climate Change Conference, aimed to keep warming above pre-industrial levels. And even though the 2 degrees limit is somewhat arbitrary, it's a goal that the world has nonetheless been working towards since then.

It really shouldn't come as a surprise that some people want to dump the limit, given the fact that just two weeks ago researchers of the Global Carbon Project wrote that the 2 Celsius goal is dwindling before our eyes, and that it was time to acknowledge the fact that the world likely won't stay on track.

Now, David Victor, a professor of international relations at the University of California, San Diego, and Charles Kennel, an atmospheric scientist at the Scripps Institution of Oceanography, argued in the journal Nature to get rid of the goal altogether.

"This has been part of this delusion that has happened in the climate policy community for the last 10 to 15 years, where people have been able to pretend that what they are doing is going to make an impact," Victor told Live Science.

Why 2 Degrees Anyway?

According to Climate Central, political officials and scientific experts agreed that this limit would "prevent dangerous" climate impacts. Former NASA scientist James Hansen and other researchers have concluded that 2 Celsius of human-made warming would trigger natural events that could end up doubling the world's warming, in fact. While this number may be bold and easy to grasp, it's not necessarily a good indicator of the impact of global warming.

So far, we've heated up the planet by about 0.85 Celsius (1.5 Fahrenheit) through the burning of fossil fuels and deforestation, which has already resulted in extreme weather events such as droughts, floods and wildfires.

It is Unachievable

But one of Victor and Kennel's main arguments is simply that this goal is unachievable.

"Owing to continued failures to mitigate emissions globally, rising emissions are on track to blow through this limit eventually," the authors wrote.

Technically, this goal is possible - though it won't be easy. Climate Central equates this energy revolution to technology, that would mean switching entirely from paper and landlines to computers and smartphones.

Countries have indeed attempted to make this climate dream a reality. President Barack Obama, for instance, proposed slashing coal emissions from US power plants 30 percent by 2030, while Beijing said it would abandon coal altogether by the year 2020.

In addition, the UN recently pledged to halve destructive deforestation by 2020, and completely end losses by 2030. Deforestation worldwide currently accounts for 15 percent of annual emission of heat-trapping gases.

Yet still, the researchers aren't impressed and say these "heroic" efforts aren't nearly good enough.

In their opinion, the 2 Celsius goal "has allowed some governments to pretend that they are taking serious action to mitigate global warming, when in reality they have achieved almost nothing," they wrote.

It is Impractical

The goal is not only unobtainable, it also oversimplifies the complexity of the climate system, Victor and Kennel claim. There is no doubt that carbon dioxide (CO2), the main greenhouse gas, traps heat in the Earth's atmosphere, thereby creating a warming world. But it is more complicated than that.

Natural variability is something that has to be considered, they say. Meaning that rises in temperature are not even and that average global temperature is not a good gauge of overall global health. High latitudes are more sensitive than the rest of the planet, which may explain why the Arctic is melting rapidly - ice loss is at its sixth-lowest level on record - even as the average global temperature has remained fairly stable since 1998.

"Most of the energy is going into the oceans, so it is not being measured as temperature in the air," Victor added to Live Science.

Do They Have Any Better Ideas?

To better account for the climate's complexity, Victor and Kennel suggest switching from the single 2-degree goal to a set of Earth "vital signs" that will better assess the planet's health.

"New goals are needed," they said. "It is time to track an array of planetary vital signs - such as changes in the ocean heat content - that are better rooted in the scientific understanding of climate drivers and risks."

"Targets must also be set in terms of the many individual gases emitted by human activities and policies to mitigate those emissions," they added.

Naturally, the paper has already been met with some criticism.

Michael Mann, a climate scientist at Pennsylvania State University, told Live Science: "It's possible that we will fail to stabilize temperatures below 2 [degrees] C warming even given concerted efforts to lower our carbon emissions, but simply discarding this goal would make failure almost certain."

Mann isn't the only one who sees their revised plan for the Earth as "misguided." Blogger Joe Romm at Climate Progress contended that "adding more vital signs just gives people more things to argue about, so it is hardly a recipe for faster or more streamlined international action."

While Victor and Kennel may or may not be right, they do point out that a window of opportunity is open. Following the UN Climate Summit that took place in New York City on Sept. 23, which hoped to restore political will for a new global climate treaty, there will be another conference in Paris in 2015 to achieve a legally binding and universal agreement on climate.

"Getting serious about climate change requires wrangling about the cost of emissions goals, sharing the burdens and drawing up international funding mechanisms," the authors concluded. "But diplomats must move beyond the 2 Celsius goal. Scientists must help them to understand why, and what should replace it."