For optimists, it was tempting to view three years of flatlining global carbon emissions, from 2014-16, as the new normal. We now know celebrations should be put on hold. Figures for 2017 published last week show global emissions from energy have jumped back up again, to a historic high.

The data from the International Energy Agency shows we still have much to do when it comes to stopping global warming. Three years ago experts cautioned that 2015’s near standstill in emissions might be only a temporary pause before resuming the upward march as India and China developed. Those warnings were prophetic.

Global energy demand last year grew by 2.1%, more than double the rate in 2016, driven largely by Asia. The problem for the climate is that more than 70% of the growth came from fossil fuels. Gas was the fastest-growing fossil fuel. But even coal, the most carbon-intensive fuel, reversed two years of declines and was up by 1%, as coal burning in China, India and South Korea grew.

To compound matters, progress on energy efficiency slowed dramatically in the face of lower energy prices and weakening government policy. On the plus side, renewables were the fastest-growing source of new energy and had another unprecedented year. China added as much solar power in a single year as the total installed capacity across France and Germany. The US scored the steepest drop in emissions, despite Donald Trump’s first year as president, as new renewable generation bloomed.

Indeed, with renewables records being broken seemingly every week – last weekend the UK set a new high for wind power – it is easy to think the fight has been won. But the IEA’s work is a sobering reminder that stratospheric growth in renewables is not enough. Renewables put a brake on emissions but they don’t stop coal, oil and gas from being dug out of the ground.

The most sobering figure in the agency’s research is 81%: the amount of global energy that comes from fossil fuels. It’s been about the same for the past three decades.

So, if the energy sector is still nowhere near compatible with the demands of climate science, and the goals set by nearly 200 governments in Paris three years ago, what do we do?

Despair is not an option, and there are reasons for hope. One is Beijing’s self-interest in tackling air quality, which means coal plant closures and bans, and the promotion of electric cars. India, the coal industry’s last great hope, has witnessed a faster than expected rise in solar power, squeezing out coal projects. Germany’s new government finally has plans to tackle the country’s outmoded reliance on coal. Globally, coal capacity will begin shrinking in 2022 at the current rate of retirements, according to a new report.

Arguably the brightest and most promising trend is that renewables are on the brink of being economically viable without government subsidies. In the UK alone, an estimated £20bn worth of wind and solar farms could be built without subsidies between now and 2030.

This year the UN is undertaking a stocktake of countries’ climate plans and it should keep the IEA numbers at the forefront of its thinking.

But getting to the top of the carbon emission mountain and down again will not be achieved solely with more favourable economics and stronger government support.

Leaders must take the much more politically difficult decision to penalise fossil fuels. The means are many: economy-wide carbon taxes are an obvious one that many energy firms claim to support. Bans on extraction of fossil fuels are a more extreme example. We must vote for those politicians who are bold enough to do this. We must renew pressure on them to say no to dirty energy, as well as yes to clean energy. Only then do we have a hope of permanently reducing emissions.

Next highlights the difficulties retailers face on a changing high street

Next boss Lord Wolfson has described 2017 as “the most challenging year we have faced for 25 years”. It was quite a statement from Wolfson, the FTSE’s second longest-serving chief executive (after WPP’s Martin Sorrell), who has a reputation for being restrained and serious-minded.

But the problems facing the high street are mounting. Last week there was a raft of bad news – New Look is closing 60 stores, axing 980 staff and cutting rent payments to landlords. Carpetright is likely to close 100 stores and also wants rent cuts. Mothercare is in talks with its banks to restructure its finances. There was a grim profits warning from Moss Bros while Conviviality – the firm behind Bargain Booze – said it needed to find £125m or was likely to go bust.

All this a few weeks after Maplin and Toys R Us collapsed into administration. Debenhams and House of Fraser also have difficulties. Each, of course, has its own problems: mountainous debts, unpaid tax bills, or merely buying the wrong stock.

But there are also major behavioural and structural issues – like the shift away from shopping towards leisure spending. Barclaycard data shows spending on women’s clothing was down 3% last year, while spending on pubs, restaurants and entertainment was up more than 10%.

Then there is the massive shift to buying online – and its impact on the bottom line. Next lost £141m of full-price high street sales last year, which resulted in lost profits of £85m. At the same time online sales rose £167m – but that generated only £32m of extra profit. So every pound lost on the high street costs the firm 60p of profit, while a pound gained online generates only 19p.

That is serious margin erosion, which many store chains and retail landlords have yet to fully acknowledge and prepare for.

Trump’s imposing tariffs on China – let’s hope he’s just talking tough

As is often the case with Donald Trump, he might think his stand against Chinese “economic aggression” will add to his reputation as a wildcard US president breaking with convention to get results.

But as has been the case before in his presidency, he ought to be more careful. Trump’s latest move of economic gunboat diplomacy – to impose punitive tariffs on up to $60bn (£42bn) of annual imports from China on certain goods – could be his biggest gamble yet.

Although the plan is to protect American manufacturers from being undercut by Chinese producers, most economists reckon it could push up prices for US consumers and lead to a damaging trade war.

Should China retaliate by imposing tariffs on US imports of soya beans or aircraft parts, as has been suggested, that would also unpick any benefit Trump may derive from imposing tariffs on China. Farmers and ranchers in the south, some of his biggest supporters, would be hardest hit.

In effect, the president is starting a giant game of economic whack-a-mole: he may find a way to fix one problem only for another, potentially greater, to emerge.

Trump has legitimate cause for concern when it comes to Chinese trade practices. China’s protectionist policies and state support for industry make it hard for other countries to compete on the world stage. The US had a record $375bn trade deficit with China last year, which made up two-thirds of a global $566bn US trade gap with the rest of the world. Chinese use of western intellectual property also undercuts US firms.

But Trump’s unilateralism risks alienating European allies from whom he might have found support for taking multilateral action against China. Throwing the EU a temporary reprieve from higher steel tariffs will not be enough to secure solid support from Brussels.

Past experience suggests trade wars can have damaging consequences, while even moderate barriers erected by several nations at once could disrupt the complex global supply chains built up in recent decades.

The world should hope Trump’s latest steps follow another well-worn path of his presidency so far: tough talk followed by measures falling short of the rhetoric.