Last week, the global climate negotiations got a shot in the arm, when two of the world’s leading industrialized economies—Germany and France—signed up to the 1.5ºC target for maximum global average temperature rise. The breakthrough means accelerated action and escalating ambition are more likely after the Paris talks. It also puts pressure on the world’s major powers to endorse a far stronger Paris outcome.

Next, Canada and Australia also signed up. Today, the United States, China, and the European Union, joined in support of 1.5ºC becoming the upper limit for global average temperature rise. The 1.5ºC standard for coordinating the global climate response is now endorsed by more than 100 countries.

As industrialized economies begin to endorse the lower temperature target, which is a higher and harder-to-meet standard, pressure is mounting to chart a pathway to full carbon neutrality at an earlier date than most observers expected from the negotiations. This can be done through various kinds of action, but the foundation for that action should be a strong Paris agreement, which defines anything above 1.5ºC as “dangerous anthropogenic interference with the climate system” and calls for worldwide carbon neutrality by 2050.

Why is this surge in support happening now? There are several reasons:

There has been a campaign, ever since evidence began to show the existential threat rising sea levels would pose to some countries, at 1.5ºC global average temperature rise, to make that the marker for dangerous human interference with the climate system. A lower temperature target means an earlier date for decisive transition away from climate forcing fuels, and we are already experiencing too much cost and too much danger. Young leaders who can see the future they will inherit are calling for a basic ethical principle of intergenerational equity, and they have been succeeding in adding crucial details to the negotiating text, which can get us a more just future and a safer climate.

A young colleague, Liz Buchan, gave a speech on this subject on Monday, where she explained the problem like this:

My colleague Maria in the island state of Kiribati already lives the reality of climate change of sea level rise, droughts, floods and more. For Kiribati, nature does not compromise on a 1.5 or 2 degree goal and Kiribati cannot be excepted to either. It is wrong for governments to continually demand Kiribati make this compromise on the foundation of their existence. My children will be close to my current age in 2050. Imagine for a moment what is at stake for someone Maria’s age in Kiribati. They cannot even be sure whether they or their children will be able to live in their rightful home. This is the human face of intergenerational equity.

There are powerful ethical reasons for taking action, but ethics has not been enough to motivate a genuine global response, so far. Now, we see a shift to a new standard mindset, where the ethics of climate-smart activities are seen as part of what builds long-term economic and political resilience. Increasingly, national climate action strategies—nationally determined contributions, or NDCs—are being designed with the understanding that mutual thriving can and must be both an ethical and an economic principle at the heart of political decision-making.

While both wealthy and resource-scarce nations face the question of higher up-front costs for meeting a stronger target, the steadily mounting costs of delayed action counterbalance that concern. There is now increased awareness about the link between degradation of the climate system, rising sea levels, and degradation of local economies and political institutions. There is now more awareness than ever of the already existing migration resulting from climate disruption, and the related social, political and economic risks.

It’s not a done deal, however. India, for instance, has resisted, arguing that the more ambitious goal will put tighter constraints on the freedom of countries now developing their industrial infrastructure to do so using the resources already in use around the world. Many see the possibility that one outcome of adoption of the 1.5ºC target will be more robust and reliable dedication of mainstream financing for low-cost economy-wide clean development.

Saudi Arabia has been accused in Paris of seeking to disrupt the negotiations, in hopes of prolonging its oil sector dominance. But there is pressure at home to build a cleaner energy infrastructure, and failure to innovate could mean a degraded economic future, as the world speeds ahead with alternative sources of energy.

The tension now emerging in the negotiations is not about whether to transition away from carbon-emitting fuels, but rather how soon to complete that transition and how quickly to get deep into it. The tension is there, because while India and Saudi Arabia and others want to develop any and all resources, it is also increasingly clear that no nation is wise to sink serious development costs in climate harming energy systems.

The 1.5ºC standard is about the future. We have a choice to build a future that makes sense for human health and wellbeing, where advanced civilization is possible, and where conflict is rare. Beyond 1.5ºC, it is not clear we can have any of that.

Liz Buchan finished her speech with these words:

We, the youth, are not recalcitrant. We are smart, passionate and organised. We know we must look climate change in the face and accept the burden it represents. I urge not only the youth but all governments and negotiators to understand each other, love each other, and lift each other into providing the solutions.

1.5ºC is a higher standard, and a stronger long-term goal, than many believed was possible at COP21. Now that this is the story of the day, the phrase on everyone’s lips, we can already see the impact on ambition. It now feels like the better choice, the smarter choice, the choice that will yield a more prosperous future, has to be 1.5ºC and the most rapid and responsible route to full decarbonization of the global economy.