Our heat-stricken planet is orbiting through the end of a year that humanity might rather forget. But several recent climate reports tell us that 2018 may be remembered as a turning point, for better or worse, in the fight to cap global warming.

Compelling new evidence shows we will speed past a dangerous climate-risk threshold as soon as 2030 if greenhouse gas emissions continue at their current rate, potentially triggering climate change on a scale that would present grave dangers to much of the living planet.

Several reports conclude that investing in a global economic transformation now would save huge amounts of money compared to paying spiraling costs for climate disasters later. Others outline the tremendous challenge: We are still shoveling millions of tons of coal into furnaces every day; CO2 emissions have increased 4.7 percent since the Paris climate agreement was signed in 2015.

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Although there were many promises of action and signs of progress as coal plants closed, renewable costs dropped and companies and state and local governments tightened their rules, the United Nations Environment Program said the gap remains as large as ever between commitments under the Paris agreement and the cuts needed to reach its goals.

IPCC: 1.5 °C Warming Is Bad; 2°C Is Worse

The climate science highlight of the year was publication by the Intergovernmental Panel on Climate Change of a report mandated by the Paris Agreement, Global Warming of 1.5 Celsius.

It authoritatively reinforces the urgent need to cut greenhouse gas emissions by roughly half in the next 12 years in order to move toward the treaty's most ambitious goal, and to eliminate emissions by 2050.

That means transforming energy, agriculture and forest systems on a large scale. It means rethinking how and where we build, work, shop, play and live; how we get around and feed ourselves; where we obtain the energy we need for economic development, and how we adapt to the global warming impacts that are ahead.

The report concludes that the impacts if the planet warms by 2 degrees Celsius compared to pre-industrial times are much greater than if we can keep warming to 1.5°C:

2°C would push extreme heat events past the upper limit of variability into a climate regime never experienced by humans, especially in the tropics.

Sea level would rise about 4 inches more with 2°C of warming than with 1.5°C, affecting 10 million more people.

2°C of warming would double or triple the species extinction rate compared to 1.5°C.

National Climate Assessment: Lots of Red Flags

After four years of work by scores of government and outside scientists, the United States issued its authoritative National Climate Assessment, which reaffirms the basic findings of the IPCC and zooms in to the impacts in the United States.

Among its findings:

With warming of 2°C or more, the U.S. can expect 9,300 additional heat-related deaths per year by 2100.

Heat waves, drought and extreme storms are impacting energy production and infrastructure, which ripples through the entire economy, including transportation, manufacturing, retail and healthcare.

Many ecosystems are at risk, including forests becoming more susceptible to fires, disease and insects.

Water and food security are threatened in many places.

The assessment, mandated by law and rigorously peer reviewed, also offers a path toward resilience and sustainability, including a series of best-practices case studies, showing how investments in adaptation and resilient infrastructure can pay off, by preserving local agriculture, reducing traffic emissions or boosting forest restoration efforts, for example.

Emissions Are Still Rising

Carbon dioxide and other heat-trapping pollution, mostly from burning fossil fuels, cause global warming, so several reports in 2018 focused on pinpointing the worst sources of the greenhouse gases, measuring how fast they are building up and also how they are absorbed by oceans, forests and fields.

All the those reports show a significant increase of emissions, which means the world is not yet on track to limit global warming, no matter how the problem is measured.

According to the 2018 Global Carbon Budget, global fossil fuel emissions increased more than 2 percent in the last 12 months. Since the Paris Agreement was signed, fossil fuel CO2 emissions have gone up more than 4 percent.

The National Oceanic and Atmospheric Administration's annual Greenhouse Gas Index, released each spring, measures the annual increase in the heating effect of all greenhouse gases combined. In 2017, the increase was 1.6 percent and since 1990. Human-caused emissions "turned up the warming" by 41 percent in less than three decades.

Biodiversity, Food Security and Extinction

In other research fields, scientists have also started identifying global warming impacts to biodiversity, and by extension, the effects on humans due to the loss of important food crops or the ecologically valuable services of species like pollinating insects and bats.

By 2070, global warming could be the main driver of biodiversity decline. Warming temperatures can affect animals directly, by changing their habitat, and also by disrupting natural reproductive cycles between species, like flowers, insects and birds.

A World Wildlife Fund study released in October found that global populations of vertebrate species have, on average, declined in size by 60 percent in the past 40 years. Habitat loss and direct exploitation are the main factors, and are linked with overconsumption of resources, which is also at the root of global warming.

In November, the European Commission Joint Research Centre suggested global warming will cause cascading extinction effects at up to 10 times the rate of existing estimates.

Scientists also showed how populations of crop-killing insects will boom with global warming, and how warming temperatures are throwing the plant-pollinator cycle out of sync.

In the oceans, hundreds of fish species are moving north to cooler water, disrupting coastal economies and threatening food supplies in less developed countries in the Global South.

In the Arctic: Rapid Changes Underway

Several 2018 reports also described how global warming continues to force rapid changes in Arctic ecosystems, including changes to ocean chemistry that are affecting marine life, as well as melting ice and thawing permafrost that is directly affecting local communities and the wider global climate system.

The international Arctic Monitoring and Assessment Program shows the Arctic Ocean continuing to become more acidic as it absorbs CO2 from the atmosphere. Among the impacts:

The changing water chemistry will affect basic biological activity in the region in ways that are still not fully understood, but there will be disruptions to the food web.

A wide range of species, from tiny plankton to shellfish, have a harder time reproducing in more acidic water, and the changes also affect their basic metabolism.

Entire ecosystems are expected to change in the coming decades as parts of the Arctic become more like adjacent temperate ocean areas.

A separate NOAA 2018 Arctic Report Card describes additional changes, including more toxic algae outbreaks, coastal permafrost erosion and a big decline of caribou herds, affecting food sources for indigenous communities.

How Climate Change Is Loading the Dice

Scientists are growing increasingly confident in linking global warming with climate disruption.

The American Meteorological Society said civilization isn't keeping up with the sweeping changes, and that leaves people vulnerable. In today's human-changed climate, extreme weather is much more likely. Studies showed:

A March 2017 extreme rain event in Peru was made 1.5 times more likely by global warming.

A five-year spike in Europe's weather extremes is linked to climate change.

Global warming is intensifying hurricanes and other tropical weather systems and is also changing the path of those storms.

Despite all the evidence, and the overwhelming scientific consensus about what it all means, the world is producing "the kind of change in emissions you would expect if we didn't know global warming was a thing," climate scientist Adam Levy said in a recent video.

What's Should We Be Learning from All This?

The massive amounts of information can seem overwhelming, but if you strip away most of the technical and scientific jargon, the message is clear, said Michigan State University professor Kyle White, who co-authored a National Climate Assessment chapter on Tribes and Indigenous People.

"The reports are all about one thing: To reach the global climate goal, we have to fundamentally rethink our relationship with the environment and realize that we aren't separate from the environment," White said.

The indigenous knowledge expressed in several of this year's reports has universal relevance for the systems-level change we need, he said. "A sustainable environment must become a basic aspect of governance. Indigenous knowledge systems are not just about recording environmental data. They're about the way society should be organized to learn from people who know about the environment," he said.

Perhaps the strongest message for climate action came from a Swedish teenager, Greta Thunberg, who mesmerized an audience of seasoned treaty negotiators from countries around the world at the annual meetings on the Paris accord.

"You are not mature enough to tell it like is," she said. "Even that burden you leave to us children."