It's not often that one of the world's biggest polluters fills me with hope that we can tackle climate change. But yesterday President Obama showed leaders around the globe what climate action looks like, and his timing couldn't be better.
In the run-up to this December's vital negotiations on worldwide climate action, we ought to be seeing bold statements like Obama's from every country - particularly those, like Britain, that have contributed the most to the problems we are now facing.
Unfortunately, our own Prime Minister appears to be doing the opposite. In the three short months that David Cameron has led his Conservative government, he has waged war on the renewables industry, on the small businesses and workers who were making our homes more comfortable and affordable to heat, and attempted to "go all out" for fracking.
We never expected great environmental progress from an austerity-obsessed Tory government, but the scale of the attack we have seen on every small step Britain has made towards fighting climate change has been galling. Instead of setting out our stall as a world leader in renewables by embracing the exciting technologies that allow us to breathe cleaner air, democratise our energy supply and enjoy greater energy security, we are now increasing our reliance on finite fossil fuels.
And worse, David Cameron still claims we need to tackle climate change.
Too often our Prime Minister talks about safeguarding our environment while scouring it for places to erect new fracking wells. Too often he boasts of leading the "greenest government ever" moments before bemoaning "green crap". Too often he offers tax breaks for the oil industry while cutting green initiatives because they are "unaffordable".
The reality is that in the sixth-largest economy in the world, we could be doing much more. It is time David Cameron recognised that it is his own policies of austerity which render renewables "unaffordable", and are wholly incompatible with the fight against climate change.
What we really cannot afford is to go on contributing to the warming of our planet, which increases our risk of dangerous storms, floods and heatwaves. By reversing austerity and creating an economy based not on maximising profits for the few, but on enriching everyone in society, we can reduce these risks.
And by doing more to cut our carbon emissions and move to a sustainable energy model, we can improve people's lives.
Instead of slashing subsidies for Britain's world-class offshore wind sector, Cameron should be offering stability and support. By investing and solar and wind energy, we can create new, highly skilled jobs that will help to rebalance our economy away from London's financial sector.
If Cameron wants to cut fuel bills, fracking and reduced building standards are not the way to go. A programme to invest in insulating Britain's homes would reduce fuel poverty, slash bills and fund thousands of new jobs in a way that would cut, not hike, our carbon emissions.
If he wants to improve our roads, he should not be building more of them. Instead he should be investing in clean, reliable and affordable public transport to reduce pollution, cut congestion and make our streets more pleasant places to BE.
The necessity of tackling climate change is not a barrier but a key opportunity to create the fairer economy Britain so desperately needs. If there was one single thing David Cameron could do to follow Obama's lead and make a strong statement ahead of December, it would be to announce significant investment and stable long-term rules to support a sustainable future.
Britain should be a world leader in tackling climate change. As it stands, it is lagging behind while the rest of the world powers ahead.