Climate activist Greta Thunberg who, at age 15, led school strikes every Friday in her home country of Sweden — a practice that caught on globally — has now, at 20, managed to bring together more than 100 scientists, environmental activists, journalists and writers to lay out exactly how and why it's clear that the climate crisis is happening.

Impressively, in The Climate Book, Thunberg and team — which includes well-known names like Margaret Atwood, George Monbiot, Bill McKibben and Robin Wall Kimmerer -- explain and offer action items in 84 compelling, bite-size chapters.

Most critically, they — and Thunberg herself in numerous brief essays of her own — explain what steps need to be taken without delay if the world is to have a reasonable chance of limiting global temperature rise as stated in the 2015 Paris Agreement. The document aims to keep the temperature rise to below 2 degrees Celsius (and better yet below 1.5 degrees Celsius).

The essays also explain why climate justice must be at the center of these efforts.

Reading The Climate Book at a deliberate pace over some weeks (it's a lot to absorb), the cumulative impact on my understanding of the crisis through its data, cross-cultural reflections, and paths for step-by-step change became mesmerizing.

If you think the rich nations of the world are making real progress towards achieving limits on global warming, think again. In one essay, Kevin Anderson, professor of energy and climate change at the Universities of Manchester, Uppsala and Bergen, puts it this way: "Wealthy nations must eliminate their use of fossils fuels by around 2030 for a likely chance of 1.5C, extending only around 2035 to 2040 for 2C... We are where we are precisely because for thirty years we've favoured make-believe over real mitigation."

What does Anderson mean by "make-believe"? In her own chapter, journalist Alexandra Urisman Otto describes her investigation into Swedish climate policy, specifically its net zero target for 2045. She discovered a discrepancy between the official number of greenhouse gases emitted each year — 50 million tons — and the real figure, 150 million tons. That lower, official figure leaves out "emissions from consumption and the burning of biomass," which means the target is way off, she writes. If all countries were off by that much, the world would be heading straight for a catastrophic increase of 2.5 to 3C.

What does that mean, emissions from consumption and the burning of biomass? John Barrett, professor of energy and climate policy at the University of Leeds, and Alice Garvey, sustainability researcher at the same university, explain that "emissions from consumption" means emissions are allocated to the country of the consumer, not the producer. Because industrial production is often outsourced to developing economies, in a world where climate justice were front and center, the consumer country (in this example, Sweden) would take the burden of lessening the emissions from consumption.

As for biomass, that refers to burning wood for energy, and sometimes other materials like kelp. Burning wood for energy causes more emissions per unit of energy than fossil fuels, explain Karl-Heinz Erb and Simone Gingrich, both social ecology professors at Vienna's University of Natural Resources and Life Sciences.

Alice Larkin, professor of climate science and energy policy at the University of Manchester, adds "a highly significant complication" to this disturbing picture: international aviation and shipping aren't typically accounted for in national emission targets, policies, and carbon budgets, either.

This under-reporting situation, I would wager, isn't known even by many climate-literate citizens. It certainly wasn't to me.

One urgent goal, then, is transparency in climate-emission figures. Beyond that, Thunberg says, distribution of climate budgets fairly across countries of the world must be a priority. Without climate justice, policies are unlikely to succeed. An especially effective subsection of the book, "We are not all in the same boat," brings this point to life.

Saleemul Huq, director of a Bangladeshi international center for climate change, puts the point squarely: The communities most devastated by climate change "are overwhelmingly poor people of colour." But Bangladeshi citizens shouldn't be thought of as passive victims, Huq emphasizes. Communities work together to prepare for the effects of climate disasters in ways not often seen in the global north. For example, "An elderly widow living alone will have two children from the high school assigned to go and pick her up" in case of hurricane or other emergency.

Globally, then, what to do? First, we can hold industrial and corporate interests accountable and push back on their messages placing the burden solely on the individual, a tactic that allows the worst of the status quo carbon-emissions activities to continue.

Beyond this, it's not enough "to become vegetarian for one day a week, offset our holiday trips to Thailand or switch our diesel SUV for an electric car," as Thunberg puts it. Participating in recycling may lead to feel-good moments, but in fact, in the words of Greenpeace activist Nina Schrank, it's "perhaps the greatest example of greenwashing on the planet today." Even the 9% of plastic that does get recycled ends up (after one or two cycles) dumped or burned.

Thunberg herself has given up flying. In the book she writes, "Frequent flying is by far the most climate-destructive individual activity you can engage in." Though she writes that lowering her personal carbon footprint isn't her specific goal in sailing (instead of flying) across the Atlantic — she hopes to convey the need for urgent, collective behavioral change. "If we do not see anyone else behaving as if we are in a crisis, then very few will understand that we actually are in a crisis," she writes.

We can join Thunberg in giving up- or at least reducing- a flying habit if we have one. Three further steps, out of many offered in the book, are these: Switch to plant-based diets. Support natural climate solutions, by protecting forests, salt marshes, mangroves, the oceans, and all the animal and plant life in these habitats. Pressure the media to go beyond the latest story on a heat wave or collapsing glacier to focus on root causes, time urgency, and solutions. Thunberg writes that "No entity other than the media has the opportunity to create the necessary transformation of our global society."

Social norms can and do change, Thunberg emphasizes. That's our greatest source of hope — but only if we keep climate justice front and center at every step.

Barbara J. King is a biological anthropologist emerita at William & Mary. Animals' Best Friends: Putting Compassion to Work for Animals in Captivity is her seventh book. Find her on Twitter @bjkingape