Since 2000, south-western North America has been in the grips of a megadrought. The severe dry spell is dramatically changing the landscape, drying up lakes and threatening water supplies.

Extreme droughts of this kind are not new 鈥� they have occurred on every continent outside Antarctica for the past 2000 years. But only recently have we started to pin down the complex global climate patterns that cause them.

In our Parched Earth series, we have taken a hard look at this unique moment for North America. We have examined what causes megadroughts, when the current one will end and what permanent scars the land will bear thereafter.

We have also considered how personal and political decisions can help or make matters worse 鈥� from reckoning with the expansion of water-intensive data centres to figuring out what gets people to use less water.

Finally, in a cover story for the US edition of our magazine, we examined the particular threat to the Colorado river and the radical proposals to save it that are finally being taken seriously. It is increasingly clear that the awe-inspiring landscapes of south-western North America will be forever altered by this extreme drought, but we still have some say in what that new future will come to look like.

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What is a megadrought?

What is megadrought? How scientists define extreme water shortages

Megadroughts are exceptionally severe, long-lasting or widespread relative to normally occurring dry stretches

When will the megadrought end?

Megadrought could become the new normal in the south-western US

Human-caused climate change is making droughts more severe 鈥� and could shift some regions of North America into permanent drought conditions

Do data centres contribute to drought?

How much water do data centres use? Most tech companies won鈥檛 say

As more data centres are being built to meet growing demand, their water use is coming under scrutiny 鈥� particularly in regions of the US affected by the ongoing megadrought

How is the megadrought changing the land?

Shocking images show scale of megadrought devastation in North America

The megadrought in south-western North America is the worst in more than 1000 years. These images from space reveal how much the severe dry spell is changing the landscape

Is climate change making the megadrought worse?

What is causing the megadroughts in North and South America?

Periods of extreme drought can be a normal part of global climate patterns, but rising temperatures may now be changing some regional climates for good

Will the land go back to how it was before the megadrought?

The US megadrought won鈥檛 just end 鈥� it will change the land forever

Patterns of drought and deluge are common throughout history, but human-driven climate change is disrupting these cycles, making it more difficult to predict exactly how the current megadought in south-western North America will end

What makes people curb their water use 鈥� and does it really make a difference?

When water runs short, how do you get people to use their fair share?

Droughts are expected to become more common and more severe due to climate change, affecting the water supply we all rely on. Making sure there's enough to go around will require significant changes 鈥� including to our individual habits

How can I cut back on my water consumption right now?

8 things you can do right now to cut back your water use

In drought-stricken areas across the globe, everyone must do their part to conserve a dwindling resource. Simple changes can help cut back on water use

How might the megadrought change society?

US megadrought could upend life as we know it 鈥� just look to history

We don't know exactly how the current megadrought in south-western North America will end, but there are examples to learn from throughout history 听

How do we save the Colorado river?

Why the Colorado river is drying up 鈥� and what we can do about it

The Colorado river is the lifeblood of the US Southwest, but today it is drastically depleted due to overuse, megadrought and climate change. Here鈥檚 how to rescue it

On 6 October, US president Joe Biden announced plans to reform US marijuana policy, including issuing a pardon of all prior federal offenses of simple marijuana possession 鈥� and calling on state governors to do the same.

鈥淛ust as no one should be in a federal prison solely due to the possession of marijuana, no one should be in a local jail or state prison for that reason, either,鈥� said Biden in . His pardon applies to thousands of people charged with marijuana possession under federal law.

He also called upon the US attorney general and US secretary of health and human services to evaluate how marijuana is classified under US federal law. Under current laws it is in the category reserved for the most dangerous substances.

The use of medical marijuana is currently legal in and Washington DC, and 19 states allow adults to purchase cannabis for recreational use. Yet despite this, many people have criminal records for simple possession of cannabis.

Such records for marijuana possession impose 鈥渘eedless barriers to employment, housing, and educational opportunities鈥�, said Biden in the statement. He also noted that despite similar marijuana consumption among different races and ethnic groups, 鈥淏lack and brown people have been arrested, prosecuted, and convicted at disproportionate rates鈥�.

Indeed, several studies support this observation. , for instance, shows that more than 53 per cent of white people over age 18 in the US report using cannabis at some point in their lives compared to 45 per cent of Black people. Yet .

In June, the American Medical Association (AMA) issued calling on states to expunge criminal marijuana charges from people鈥檚 records when the related offences were later legalised.

鈥淚t simply isn鈥檛 fair to ruin a life based on actions that result in convictions but are subsequently legalized or decriminalized,鈥� said AMA spokesperson Scott Ferguson at the time.

Book

Fuzz: When nature breaks the law Mary Roach

WW Norton

MARY ROACH has a knack for choosing subjects for her books that won鈥檛 have necessarily crossed your mind and convincing you that you must now know everything about them. She has covered the logistics of strapping cadavers into cars to use as human crash test dummies (), how studying what orgasms look like in the brain requires people to get busy in an MRI scanner (), pondered the literal ins and outs of what competitive eating does to your digestive tract () and contemplated how astronauts poop in space (, a rare deviation from her single word titles).

In her new book, , her subject is the unfortunately now familiar issue of human-wildlife conflict. But she hasn鈥檛 decided to switch gears and approach her subjects from a place of earnest lamentation, in this case about the perils of our encroachment on wild habitats. Instead, with her characteristic dry wit, she brings an intense fascination to the seldom discussed details and the at times absurd miscellany in the unexplored corners of unappreciated research.

The opening chapter finds her at a wildlife forensics conference, where she learns about what happens after a human is mauled by a wild animal. The focus of the Wildlife-Human Attack Response Training conference is mainly bears in the Pacific Northwest. We learn that very often the culprit is identified and killed, but occasionally the backwoods whodunnit turns up a surprise: a 鈥済nawed on corpse鈥� is no smoking gun. An opportunistic omnivore does occasionally stumble on a human already dead from other causes.

Each chapter explores a new type of conflict, from elephants that stomp their way across crops (and people) to albatrosses that get sucked into jet engines, leopards that attack people to deer that collide with aircraft (yes, you read that right).

Along the way you pick up plenty of helpful tips. The best makes of car if you plan to survive crashing into a moose? Saab or Volvo. The most cost-efficient way to keep birds from eating your harvest on a small farm? Humans regularly chasing them off.

As to whether you should stay still or fight back in a hostile bear encounter, it largely depends on what kind of bear it is, 鈥渂lack fight back, brown lie down鈥� as the ditty goes. The trouble is, as Roach points out, some brown bears鈥� fur can be black, and some black bears look pretty brown.

鈥淚t鈥檚 impossible not to smirk, chortle and sometimes outright belly laugh as you read the many wry asides鈥�

鈥淎 more reliable way to distinguish the two is by the length and curvature of their claws,鈥� she says, before conceding that, 鈥渂y the time you鈥檙e in a position to make that call, the knowledge will be of limited practical use.鈥�

It is impossible not to smirk, chortle and sometimes outright belly laugh as you read her many wry asides and funny but fascinating footnotes.

A particular favourite for me has to do with the surprisingly persistent myth that birds will explode if they eat the rice tossed at weddings: 鈥淪ome churches ban the practice anyway, not because it鈥檚 perilous for birds but because it鈥檚 perilous for guests, who could slip on the hard, round grains and fall and then fly off to a personal injury lawyer.鈥�

She provides an ample supply of factoids to regale your friends with. Did you know that it is our 鈥渓ooming sensitivity鈥� that helps us and other animals anticipate how fast something is coming at us, so we can get out of the way? (Or not, see the earlier mention of deer and aircraft.)

But the real trick Roach pulls off is to keep you laughing while at the same time making sure the earnest points come across. Among the many that stuck with me is that before the 1980s, wildlife and wilderness were conserved in the US to provide good hunting and fishing. It is only recently that 鈥�conservation鈥� has been about protecting these areas and creatures for their own sake.