The draft version of the US National Climate Assessment, released on Friday, makes remarkable reading – not just for Americans but for all humanity. Put together by a special panel of more than 240 scientists, the federally commissioned report reveals that the US is already reeling under the impact of global warming. Heatwaves, droughts, floods, intense downpours, rising sea levels and melting glaciers are now causing widespread havoc and are having an impact on a wide range of fronts including health services, infrastructure, water supply, agriculture, transport and flood defences.

Nor is there any doubt about the cause of these rising temperatures. "It is due primarily to human activities, predominantly the burning of fossil fuel," the report states. As carbon dioxide levels in the atmosphere soar, temperatures rise and chaos ensues. Air pollution intensifies, wildfires increase, insect-borne diseases spread, confrontations over water rights become more violent and storm surges rise. This is the near future for America and for the rest of the world. Earth is set to become a hotter, drier, unhealthier, more uncomfortable, dangerous and more disaster-prone place in coming years.

The language used in this exhaustive, carefully researched investigation is also worthy of comment. It includes the word "threat" or variations 198 times and versions of the word "disrupt" another 120 times. After poring over the 1,146 pages of the assessment, readers will be under no illusions about what is happening to our planet. The robustness of its rhetoric is especially striking because it contrasts so noticeably with the debate – or to be precise, lack of debate – on climate change that occurred during last year's presidential campaigning.

Neither President Obama nor his opponent, Mitt Romney, made more than a cursory mention of the issue, despite the fact that it now affects just about every aspect of existence on our planet today. As the assessment makes clear, global warming is not just about polar bears. It is about the lives of people today and about those of future generations.

A three-month period for public comment will now follow last week's publication of the draft assessment. The US National Academy of Sciences will also review the document before a final version is published later this year. The ensuing debate promises to be an intriguing and important one. The US is the world's greatest economy and a massive emitter of greenhouse gases. Until its political masters act, the planet has no chance of halting global warming or curtailing rising sea levels or dealing with the increasing acidification of our oceans or coping with the melting of Earth's icecaps.

Given the vehemence of opposition in the US to the suggestion that climate change is manmade, we should not be too hopeful of immediate action. Most of the Republican party believes the concept is a liberal hoax, for example, along with an array of rich and powerful industrial foundations and corporations. A bitter struggle lies ahead.

From this perspective, it might be tempting to sneer at the US over its response to the challenge of climate change. Britain has little to be smug about, however, a point that was demonstrated last week by media coverage of the Met Office's updated forecast of likely global warming over the next five years. In revising downwards, albeit slightly, its previous expectation for temperature rises from now until 2017, the Met Office found itself at the midst of a PR shambles. In their dozens, climate change sceptics charged forwards to claim this data showed that global warming has stopped, a completely misleading suggestion that was not properly challenged by journalists.

In fact, the Met Office's figures indicate that most of the years between 2013 and 2017 will probably be hotter than those of the hottest year on record. More to the point, British forecasters still stand by their longer-term projections that anticipate there will be significant warming over the course of the century.

The fact that this message was lost on the public suggests climate change denial is becoming entrenched in the UK, or that our media have become complacent about the issue, or both. Whatever the answer, there is little cause for cheer. Both sides of the Atlantic are dithering over global warming. Yet the issue is real, as the US climate assessment emphasises. In making that clear, the report should be welcomed.

• This article was amended on 22 February 2013 to insert the word "probably" in the sentence that now reads: "In fact, the Met Office's figures indicate that most of the years between 2013 and 2017 will probably be hotter than those of the hottest year on record."