G7 leaders share a bold vision for a net zero future. But the devil is in the lack of detail

US President Joe Biden, center, and other G7 leaders arrive for a photo during a reception at The Eden Project in England on June 11, with Queen Elizabeth II, left.

Falmouth, England (CNN)Climate change is rarely a main talking point at the G7 leaders' summit, but as US President Joe Biden proclaimed that "America is back at the table" on the final day of this year's meeting, by extension, so too was climate change.

Past summits with Donald Trump representing the United States struggled to culminate in cohesive group statements between its members -- the US, UK, France, Germany, Italy, Japan and Canada, plus the European Union. But in the English county of Cornwall over the weekend, leaders appeared to agree that this is the crucial decade that will determine the world's future, even its very existence.
There was concrete progress earlier in the summit from G7 ministers, and a vision laid out by leaders for a net zero world (where all greenhouse gases emitted are removed from the atmosphere) that would take a green approach to everything, from the economic recovery from the pandemic to the way new infrastructure is built in the developing world.
    Climate activists Delores and Leroy Tycklemore wear bee keeping suits in a protest in Falmouth, England, on Friday, June 11.
    What was lacking in the final communiqué, however, was the detail that climate change experts were hoping for.
      G7 meetings are notorious for making bold promises only to break them. Often world leaders' vision just isn't backed by lawmakers at home.
      This year, there were some ambitious collective targets, to halve emissions by 2030 from 2010 levels, for example, but no individual country increased its commitment to reduce greenhouse gas emissions, and goals were set with no firm deadlines or measurables. In cases where they were, they were largely underwhelming.
      The leaders said, for example, that they would aim to reach net zero by 2050 at the latest. That's about 20 years too late, according to Catherine Pettengell, interim head of the UK's branch of Climate Action Network, which represents more than 1,500 civil society organizations in over 130 countries.
        "We were really expecting to see the G7 step up and send a strong signal ahead of COP26 that they've really done their homework and were ready to act," she told CNN, referring to international climate change talks planned in Glasgow later this year.
        She is particularly concerned about the lack of progress on a climate finance fund agreed to more than a decade ago. By 2020, developed nations were supposed to start transferring $100 billion a year to the developing world to help them adapt to climate change. The idea was that wealthy countries had historically done more to contribute to climate change while poorer nations will be worst affected by its impact.
        The world missed that 2020 deadline and is still way off keeping its promise. The US and UK had already doubled their annual contributions, and over the weekend, Germany and Canada at least doubled their pledges too. The other G7 members are lagging.
        "Even with new announcements from Germany and Canada, all G7 countries need to go further and faster with their individual commitments as well as take collective responsibility for achieving the $100 billion goal before COP26," Pettengell said.
        "They acknowledge in the communiqué that more commitments must come by COP. So I think the question is, 'Why not now? What's the delay?' Developing countries deserve to have the confidence going into COP 26 that the Paris Agreement will be delivered. And it can't go down to the wire. These leaders need to prioritise building trust and momentum now with the four and a half months left to COP 26."
        There's a lot at stake. Carbon emissions are at their highest level in history, despite more than a year of the world's economies slowing during the pandemic. The goal is to keep global warming to 1.5 degrees Celsius above pre-industrial levels. The Earth is already at 1.3C, and if it exceeds that threshold, millions more people will be at risk of extreme heat waves, drought and flooding. Food shortages will worsen. Entire species will face extinction. Coral reefs will all but disappear.