Bringing species like beavers (河狸) back to England is no longer a priority, the government said on Friday to criticism from wildlife groups.

A recent report shows that one in six UK species are at risk of extinction. In September more than 60 conservation organizations reported a significant decline in species due to expansions in farming and the effects of climate change. In recent years, animals and plants have been reintroduced by charities as part of efforts to restore the country’s reduced biodiversity.

Despite the government allowing this, the Environment, Food and Rural Affairs Committee concluded in July that there was an absence of long-term plans on how to manage this. In response, the government has now said that the "reintroduction of species is not a priority".

The government said it was focused on increasing biodiversity through habitat restoration. The government's environment department has come under scrutiny (详细审查) for not doing more to prevent sewage dumping and other forms of pollution in England's waterways.

Sir Robert Goodwill, chair of the Committee, said he was disappointed with the government response. Bringing back extinct species is a controversial issue- although farmers and landowners appear broadly supportive, there are risks of reintroducing new species, and without clear guidance, problems could arise.

A recent study showed that river barriers similar to those built by beavers can protect communities at risk of flooding. But there have also been cases documented in Europe where beavers have built their dams in places that have damaged crops and changed rivers.

Joan Edwards, director of Policy &Public Affairs at The Wildlife Trusts said, “Reintroducing wildlife must be part of the UK government’s arsenal (武器) for tackling nature loss and climate change—it is astonishing there is no strategy for doing so.”

“The return of wild beavers can help to recreate lost wetlands, with a knock-on effect that benefits other wildlife including insects, invertebrates and birds. Beavers also slow the flow of water, which can reduce flood risks to towns and villages,” she said.

As the COVID-19 pandemic （新冠肺炎）rages, with ongoing lockdown （封城）measures affecting millions of people around the globe, levels of air pollution are falling dramatically in many parts of the world. This trend has been highlighted by a new report published by Swiss company IQAir looking at ten key global cities that normally suffer from high levels of pollution.

The report compared measurements from ground-based monitoring stations regarding a type of pollutant known as PM2.5— tiny inhalable particles measuring 2.5 micrometers or smaller that are emitted （排放）by various sources such as vehicles and power plants. It found significant falls in nearly all the locations listed.

This is, perhaps, not surprising considering the large decreases in vehicle traffic and industrial activity that have occurred with lockdown measures imposed （实施）on these cities.

The report examined data collected over a three-week period for each city while they were under lockdown conditions. IQAir then compared these measurements to the same time period for the years between 2016 and 2019.

IQAir found that nine out of the ten cities in the report experienced significant reductions in PM2.5 compared to the same period for 2019. Those with historically higher levels of PM2.5 pollution saw the greatest drops including New Delhi （-60 percent） Seoul （-54 percent） and Wuhan （-44 percent）. Besides, seven of the cities saw reductions in PM2.5 of 25 to 60 percent compared to the same period last year.

Wuhan—where the COVID-19 pandemic was first identified—experienced the cleanest air on record for February and March. The city was placed under one of the strictest lockdowns in the world on January 24, which was only lifted after 10 weeks.

Unfortunately, these sharp improvements in air quality have coincided （同时发生）with significant economic disruption, suffering and loss of life across the globe. Furthermore, experts warn that without sustained action to control pollution once the crisis ends, levels will likely rebound, as has been witnessed following previous economic downturns.

In 1960 the Aral Sea was one of the world’s largest inland water bodies, covering an area of approximately 68,000 square kilometers (26,000 square miles). By the year 2000 the area covered by the Aral Sea had become less than half its 1960 size, its volume reduced by 80 percent. By about 2010 all that will remain will be three shallow remnants.

What caused the Aral Sea to evaporate over the past 40 years? As recently as 1965, the Aral Sea received about 50 cubic kilometers (12 cubic miles) of fresh water per year. By the early 1980s this number had declined to nearly zero. The reason was that the waters of the Amu Darya and Syr Darya had been diverted to supply a major expansion of irrigated agriculture in this dry realm.

The intensive irrigation has greatly increased agricultural productivity, but not without significant costs. The deltas of the two major rivers have lost their wetlands, and wildlife has disappeared. The once thriving fishing industry has been eliminated, and the 24 species of fish that once inhabited the Aral Sea are no longer there. The shoreline is now tens of kilometers from the towns that were once fishing centers.

The shrinking sea has exposed millions of acres of former seabed to sun and wind. The surface is covered with salt and agrochemicals brought by the rivers. Strong winds routinely pick up thousands of tons of newly exposed materials every year and deposit them throughout the region. This process has not only contributed to a significant reduction in air quality for the region’s population, but has also appreciably reduced crop yields due to the deposits of salt-rich sediments on farmable land.

The shrinking Aral Sea has had a noticeable impact on climate. Without the moderating effect of a large water body, there are greater extremes of temperature, a shorter growing season, and reduced local precipitation. These changes have caused many farms to switch from growing cotton to growing rice, which demands even more diverted water.