SINGAPORE - Wednesday (April 22) is Earth Day but it is not like any Earth Day since the event started 50 years ago.
Around the world, millions of people hunkered down in their homes are marvelling at the blue skies outside and near-empty roads.
Air pollution has plunged in major cities and industrial belts, rivers are running cleaner and birdsong can be heard more clearly, no longer drowned out by relentless traffic.
Greenhouse gas emissions have also dropped markedly and oil demand has fallen off a cliff.
In a matter of weeks, the global economy and people's lives have been tipped upside down, giving the planet a breather and showing what things could be like if humanity really valued the environment and ended its reliance on polluting fossil fuels.
In a perverse way, the pandemic has opened that window.
Much of environmental benefits are likely to be temporary once the lockdowns across the globe are lifted.
The question is will everything go back to the way it was or will there be lasting change?
Dr Ralph Keeling, a geochemist from the Scripps Institution of Oceanography in the United States, said on Twitter that fossil fuel use would have to decline by about 10 per cent around the world and would need to be sustained for a year to show up clearly in levels of carbon dioxide, the heat-trapping gas that is causing global warming.
Whether or not this would happen is still hard to answer.
But already there have been loud calls by the EU and others for the massive stimulus packages to include spending on clean energy and on more sustainable projects.
And the images of blue skies and satellite imagery showing the marked drop in deadly air pollution have opened many eyes.
Of course, the radical changes have been forced upon people and businesses, so any lasting change will need to have widespread consensus.
But twinned with accelerating threats from climate change and escalating damage to the environment, the pandemic and the recovery phase represent a huge opportunity to rethink and reset the way we live and how our economies work.
Because the Earth's vital signs are not good.
Last year, a global assessment of life on earth found that nature is declining at an unprecedented rate and the pace of extinction of plants and animals is accelerating, putting at risk economies and the well-being of all people.
Up to a million species are threatened with extinction, said the report from the UN's Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services.
That matters because mankind cannot exist without nature. Forests, oceans, grasslands, coral reefs and other ecosystems provide the food, water and air we need to survive and the resources for our economies.
"Every breath of air we take, every mouthful of food we eat, depends upon a healthy natural world," says British broadcaster and natural historian David Attenborough in a video to mark Earth Day.
And as a global conservation group, BirdLife International, pointed out on Wednesday, the health of the environment is closely intertwined with human health.
The Covid-19 pandemic, which has been linked to the sale and consumption of wild animals for food, was but one symptom of an ailing Earth.
A series of landmark reports by the UN's peak climate science body, the Intergovernmental Panel on Climate Change (IPCC) in 2018 and last year, underscored the climate risks and the urgent need to overhaul the way we grow food so as to ensure less waste and to end wholesale destruction of forests, wetlands and grasslands - ecosystems which can help fight climate change.
Of the 7.8 billion hectares of arable land on the planet, already two billion hectares are degraded, the UN Development Programme says.
Climate change, land degradation, water shortages and worse droughts are expected to drive up the number of refugees and trigger conflicts.
The IPCC says humanity has to make deep cuts in greenhouse gas emissions this decade to have a reasonable chance of limiting global warming to 1.5 deg C above pre-industrial levels.
Exceeding that level will bring accelerating loss of coral reefs, falling crop yields, more powerful storms and floods, and faster sea level rise.
The global average temperature has already risen 1.1 deg C since pre-industrial times and last year, emissions of carbon dioxide (CO2) reached another record high, mainly through burning of coal, oil and gas.
There is no time left to dither, says the UN, with the effects of climate and change and biodiversity loss at alarming levels.
Record high sea temperatures in February along Australia's Great Barrier Reef, the world's largest, has caused the third mass coral bleaching event in five years, adding to severe damage caused in 2016-17.
Globally, parts of the Atlantic, Pacific and Indian Oceans all hit records for warmth last month.
The good news is action is being taken and there are solutions. But the action needs to speed up quickly.
Globally, renewable energy investment is growing.
Last year, almost three-quarters of new electricity generation capacity built used renewable energy, representing an all-time record, according to data from the International Renewable Energy Agency (Irena).
The data shows solar, wind and other green technologies now provide more than one-third of the world's power, also a record.
The agency also says governments can speed up phasing out fossil fuels in the energy system and revive economies hit by the coronavirus if they tailor stimulus packages to boost clean energy technologies.
In a report published on Monday, Irena said if the world boosted funding on energy systems from 2016 to 2050 to US$130 trillion (S$186 trillion) and focused on renewables, energy efficiency and electrification, it could boost economies and create millions of jobs.
Irena found that each US$1 spent on the energy transition would yield a return of US$3 to US$8, by curbing the costs associated with the devastation caused by climate change and the deadly health impacts of air pollution.
Elsewhere, the transition away from coal is gathering pace, with 21 financial institutions this year announcing policies to end or limit finance for new coal projects.
In the past week, Citigroup and Japan's second and third-largest lenders - Mizuho Financial Group and Sumitomo Mitsui Financial Group (SMBC) - unveiled their pledges.
Globally, financial institutions are progressively restricting or ending financing to fossil fuel investments, while hundreds of cities have committed to achieving net-zero emissions by 2050.
Youth climate groups and environmental shareholder advocacy organisations are also pushing for environmentally friendly policies and practices inside boardrooms.
For now, most people are just focused on living and planning for when lockdowns end.
But some have already decided that they want the blue skies to remain.
According to The Guardian, Milan plans to introduce one of Europe's most ambitious schemes reallocating street space from cars to cycling and walking, in response to the coronavirus crisis.
The city announced on Tuesday that 35km of streets will be transformed during summer, with a rapid, experimental citywide expansion of cycling and walking space to protect residents.
