Science is under attack at the very moment when we need it most. President Donald Trump’s March 28 executive order went much further than simply throwing a lifeline to fossil fuels, as industry-funded congressional climate change–deniers have done in the past. It intentionally blinded the federal government to the impacts of climate change by abolishing an interagency group that measured the cost of carbon to public health and the environment. Now, the government won’t have a coordinated way to account for damages from climate change when assessing the costs and benefits of a particular policy.

With that in mind, Trump should read the landmark “2020” report now published by Mission 2020, a group of experts convened by the former Executive Secretary of the United Nations Framework Convention on Climate Change. The report establishes a timeline for how we can ensure a safe and stable climate. We don’t have much time — 2020 is a clear turning point.

If emissions continue to rise beyond 2020, the world stands very little chance of limiting global warming below 1.5 degrees Celsius, the threshold set by the Paris Agreement, and a temperature limit that many of the world’s most vulnerable communities consider a threshold for survival. We have four years to bend the curve of global greenhouse gas emissions toward a steady decline.

The good news is, we’re already moving in the right direction. Global carbon emissions have plateaued, and are projected to remain flat over the coming years, thanks to China’s widespread economic transformation and the global boom in renewable energy production. The 2020 climate turning point is within reach.

But, as the authors of the report reveal, the bad news is we aren’t moving fast. Thankfully, there is a range of actions that, if achieved, can deliver a safe future. The study shows that by 2020, renewable energy must beat out coal in all major energy markets. Countries must commit to electrifying the transportation system, and transmission infrastructure must be built out to host efficient, low-carbon energy systems. Deforestation must be reined in, and the restoration of already degraded land must be well underway. All of the Fortune 500 companies that represent heavy industries must have committed to the Paris targets, and their emissions-reduction plans must be in effect. And, finally, capital markets must double investment in zero-emission technologies.

Around the world, more and more politicians are listening to scientists. Nearly 200 heads of state adopted the Paris Agreement in December of 2015, and 136 have since ratified the deal in record time. Leaders in China and India have redoubled investments in renewables, and investors across the developed world are walking away from coal. And last fall, all 197 parties to the Montreal Protocol adopted a critical amendment that will phase down Hydrofluorocarbon, a particularly potent greenhouse gas.

Even in the United States, where public concern about climate is high but doubt of the scientific consensus on climate change has also spiked in recent years (I should know, having recently testified to the climate change–denying chair of the House Science Committee), and where the new Administration wants to stop funding climate science, many politicians are redoubling their commitment to climate action. From mayors of major cities to Congressional Republicans to the Defense Secretary, serious policy responses are being debated.

The only way to avoid dangerous climate change, and to keep the 1.5 degree Celsius target in play, is to step up our ambition by 2020, and deliver emissions reductions across all sectors. Only by drawing down global carbon emissions, by making sure that they drop steadily from 2020 forward, can we ensure that the world avoids the worst fates of climate change.

Science has no political affiliation and shouldn’t be a political issue. Chemistry and physics don’t care who is president or which party runs a parliament. No politician should ignore the warnings of scientists, economists and military leaders, and argue against health, increased stability and economic prosperity — all of which depend on how the world responds to climate change.

There is no denying it: 2020 will be a very important year.

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