A few days ago WWF revealed that over the last few decades, the number of marine vertebrates in our seas has halved. Bird, fish, reptile and mammal populations in our seas have declined so precipitously because we have been taking more than the planet can provide or replace. As a result, global food security and the livelihoods of countless people are on the line as stocks of fish - the primary source of protein for 1 billion people in developing countries - plummet. It's hard to think of a more potent illustration of how humans and nature are intertwined, and of the need for all of us to start doing things differently.
This week David Cameron joins leaders from around the world at the UN headquarters in New York to adopt the Sustainable Development Goals (SDGs) to beat poverty, hunger, injustice and environmental destruction by achieving sustainable development that benefits everyone without wrecking the planet. WWF has long understood that we need to protect our environment to make social and economic progress possible in the long term. There seems finally to be global consensus around this truth, with explicit SDGs on climate change, sustainable consumption and production, forests, oceans and other habitats as a key part of the new package.
For too long, governments have been following the beguiling path of economic growth at any cost. The consequences - from growing inequality, damaging pollution and dangerous climate change to the loss of more than half of wildlife populations in the last 40 years - have been devastating. Could this, then, be the point at which the world wakes up, and changes course? No doubt the Prime Minister and his global contemporaries will have some reassuring words at the UN when they make their speeches this week. But - if they want to prove they are serious about the SDGs - governments, including our own, will have to make some serious changes when they return home.
An early test will be the UN Climate conference in Paris. The 2030 Agenda, which includes the SDGs, clearly calls for an ambitious and universal agreement with legal force that closes the emissions gap and keeps global warming below 2 or 1.5 degrees. As the Prime Minister has repeated, tackling climate change is a pre-requisite to ending poverty and achieving sustainable development. His speech at the UN this week end is an opportunity to set the stage for Paris. For example, he could pledge the UK's fair share of climate finance to help developing countries adapt to the effects they are already feeling, and announce the date by which the use of unabated coal will be phased out in the UK.
Likewise, the sound management of natural resources and natural capital - our forests, oceans and other habitats - will have to become the bedrock of domestic economic policy. This means that the Treasury will assess the impact of every policy, from infrastructure to tax, to account for their true costs to people and the planet, and to ensure that the environment is no longer an afterthought but a mainstream priority at all levels of government. How would this affect recent decisions to favour fossil fuels rather than energy efficiency and renewables? George Osborne will need to dig deep and find passion for the environment in his heart.
Internationally, DFID will have to work hard to help deliver the SDGs in developing countries. But Ministers will have to ensure that UK policy across all departments - for example, trade policy and the procurement of goods and services from overseas - impacts positively on the rest of the world. This means supporting countries to develop 'beyond aid', so they can mobilise their own resources from tax in the long term; and it means enabling wider investment flows and trade to high standards of sustainability so that the UK supports genuinely sustainable development.
In short, the ambitious SDG agenda will remain aspirational words unless the Prime Minister makes their implementation a priority for every government department, and backs that up with his personal authority. A good starting point would be to charge the Cabinet Office with coordinating implementation across all departments, and to publish a clear and costed plan setting out how the goals will be delivered in, as well as by, the UK. Then we'll know that the Prime Minister has the courage and commitment to make good on his fine words in New York.