Earth Day is today, and this year it's a historic one.
Over 150 world leaders are gathered at the United Nations in New York to sign a landmark climate agreement.
The accord was adopted in Paris late last year, aimed at cutting global greenhouse gas emissions and slowing the warming of the planet.
Now countries actually have to meet those emissions targets.
Cara Horowitz, co-executive director of the Emmett Institute on Climate Change and the Environment at the UCLA School of Law, joined Take Two to explain what comes next after today's signing:
What makes the global climate accord so significant?
These countries agreed to a new international accord with the goal of keeping global warming to well below 2 degrees Celsius. And for the first time they agreed to a structure where every country around the globe pledges to reduce emissions. So this isn't like the predecessor to this agreement which is the Kyoto Protocol where only developed countries had obligations. The structure of the agreement has countries pledging every five years, and the content of those pledges is really self-generated.
How will countries be held accountable for their pledges?
It's really an agreement that works by naming and shaming in some senses. So countries come to the table, the make pledges about what they'll do, and then they report every couple of years about what they've achieved or what they haven't. But there's really no legal mechanism for forcing countries to cut emissions if they wouldn't otherwise do so. Instead it's really about incentives. There's a lot of funding on the table for example.
Today's signing is just a step in the process, right? What needs to happen next for countries to formally join the accord?
Countries are signing today. This is the largest number of countries that have ever signed an international agreement in one day. And by its own terms, the Paris agreement comes into effect when 55 countries representing at least 55 percent of global emissions have signed and ratified. And so they're signing today, in order to ratify, the countries need to actually formally submit the pledges that they're making.
When will that happen?
I expect that will happen quickly, so the Paris agreement I think is likely to come into effect in the next 30 days.
Where are we on the goal of bringing down pollution levels so that global temperatures don't rise more than 2 degrees Celsius above preindustrial levels?
So MIT and others have done analyses taking a look at the pledges that have been made in the aggregate under the Paris agreement so far and it looks like no. Somewhat not surprisingly, this first round of pledges by countries, even if countries were to achieve everything they've said they will achieve under their pledges, doesn't get us by itself to the 2 degree goal. It looks like maybe, if we're lucky, it would keep us to something like 3 or 3 1/2 degrees of warming. But even that by itself is significant.
This agreement, and the signing of this agreement, isn't success by itself, but lots of people think it's what the beginning of success probably looks like. If we're going to change global energy economies and transition to low carbon economies, this is how you start to do it.
If all these countries meet their goals, and continue to meet their goals, when do you think we could begin to see a change?
So Christiana Figueras, who is the Executive Secretary of the group that created this agreement, has compared the world's energy infrastructure to a huge tanker on the ocean. She says it doesn't turn on a dime, but it can be turned. It'll take maybe 50 or 60 years, people are looking at maybe the end of the century before we get to a place where we've decarbonized our economy. The problem with climate change is you still then have greenhouse gases in the atmosphere that live on for many many decades, and we continue to feel the effects of the warming created by those gases even after we've stopped emitting. So this is a long-term problem, it will take a while to solve, but this is definitely an important first step.