100 million Americans under air-quality alerts - plus other nature and climate stories you need to read this week

More than 100 million Americans were under air-quality alerts on 29 June, as smoke from Canadian wildfires spread out across the Midwest and east of the US, darkening skies and putting health at risk.

They were urged to limit time spent outside and wear a mask if they suffered from respiratory diseases, while children and the elderly were cautioned to limit exercise, Reuters reports.

Cities from New York to Philadelphia saw smoky skies that dulled the summer sun as the smell of burning wood lingered in the air.

"This is the new normal for New Yorkers," said New York Governor Kathy Hochul, warning that air quality was unhealthy in 'every corner of the state'.

Canada is experiencing the worst start to wildfire season on record, with an area of almost 20 million acres having already burned.

China formally accepted a World Trade Organization (WTO) agreement aimed at curbing harmful fisheries subsidies.

The announcement by the world’s top fishing country was made at the World Economic Forum’s 14th Annual Meeting of the New Champions (AMNC) in Tianjin, China on 28 June.

“China's support for the implementation of this agreement is critical to multilateral efforts to safeguard oceans, food security and livelihoods,” WTO Director-General Ngozi Okonjo-Iweala said in a statement.

The world lost an area of tropical primary forest the size of 11 soccer pitches per minute in 2022, according to the latest Global Forest Watch report from the World Resources Institute.

Overall, 10% more tropical rainforest was lost in 2022 than in 2021, despite 145 committing to end and reverse forest loss by 2030 in the Glasgow Leaders’ Declaration on Forests and Land Use at COP26.

Global Forest Watch, which draws on forest data collected by the University of Maryland, found 4.1 million hectares of tropical rainforest was lost in 2022, producing 2.7 gigatonnes (Gt) of carbon dioxide emissions, or roughly the same as India's annual fossil fuel emissions.

United Nations Secretary-General Antonio Guterres has called for the shipping sector to speed up decarbonization efforts and agree to reach net-zero emissions by 2050. Member countries of the UN's shipping agency, the International Maritime Organization (IMO), are meeting in London this week.

It comes after London Climate Action Week came to a close on 2 July. In the lead-up to the event, Razan Al Mubarak, UN Climate Change High-Level Champion for COP28, urged business leaders to take five actions to put nature-positive solutions higher on the global agenda.

A global initiative aiming to bring transparency and confidence to the unregulated carbon offset market has introduced a Claims Code of Practice. The Voluntary Carbon Markets Integrity Initiative's code, supported by the British government, aims to help investors determine the credibility of companies' claims regarding progress towards internal climate targets and their use of carbon offset credits.

Rising temperatures and pollution threaten more than 90% of the world's marine food supplies, so-called 'blue food', which includes shellfish, plants and algae, according to a study published by Nature Sustainability.

A three-week-long heatwave in Mexico has claimed at least 100 lives, with temperatures rising to almost 50 degrees Celsius, according to the health ministry. Two-thirds of the deaths occurred in the week commencing 18 June, with only one heat-related death being registered in the same week last year.

On a visit to Kyiv on 29 June, Swedish climate activist Greta Thunberg said the world's reaction to the 'ecocide' caused by the collapse of the hydro-electric Kakhovka dam was inadequate. "We have to talk louder about it, we have to raise awareness about what is going on," she said.

Fixing the environmental damage caused by deep-sea mining would cost twice as much as extraction, according to a new report published on 29 June, and would have an impact on biodiversity up to 25 times greater than land-based mining.

Data shows that protected forests store 28% more carbon than ecologically similar but unprotected forests. They also absorb and capture carbon more than new technologies attracting billions in funding. The voluntary carbon market could be a crucial source of financing to help bridge resourcing gap for protected forests write two experts from Conservation International.

Saving the ocean and protecting the $3 trillion ocean economy requires money - but it's an opportunity, too. Lubomir Varbanov, Managing Director and Head of Public Sector Solutions at Swiss Re explains how China and other countries can expand their investments in blue finance.

Transitioning to clean energy means also transitioning our understanding of value from being profit-driven to centred on environmental and societal gains. Data can enable companies to drive environmental, social and corporate governance (ESG) goals with a new economic model, writes Dasami Moodley, NAX Group's Director and Head of Sustainability.