This week’s environment round-up looks at the search for sustainable wellbeing, the vast fungal networks keeping ecosystems alive, and the likelihood of warming exceeding 1.5°C before 2030.

Females lead way to environmentally sustainable human wellbeing

The Health Planet Index (HPI) measures how successfully nations are achieving sustainable wellbeing now, while ensuring that others can do the same in the future. Countries that are performing well achieve high levels of health and life satisfaction (referred to as “Adjusted Happy Life Years”), while maintaining low ecological impact. The latter is measured as the global hectares (gha) of the planet’s surface required to sustain an average resident’s consumption pattern.

Another way of looking at the HPI is as a measure of how much wellbeing is achieved per unit of environmental resource consumed. Mathematically, it is represented as:

HPI = (Life expectancy X self-reported wellbeing (Adjusted Happy Life Years)) ÷ ecological footprint

The 2026 Healthy Planet Index report presents data for 134 countries up to 2025.

No country achieves “sustainable wellbeing”. The highest ranking country is Costa Rica with an HPI of 68 per cent. Then there’s a sharp drop to 60 to 61 per cent for the next seven countries. There are distinct continental-scale patterns evident in the map below. Latin America stands out as the best performing region, followed by Europe. Asia is mixed. North America, Australia and Africa are poor performers.

The graph below is a scatter plot of Adjusted Happy Life Years and Ecological Footprint. Some countries are doing better than others at achieving high levels of health and happiness, while some are better at keeping their ecological footprint low. Some are even moving toward both good health and a low footprint. (It’s important to note that the scatter plot indicates an association between the two variables, not a causative relationship.)

Australia achieves very good health but with an unfortunately high demand on the environment – hence its low HPI.

The plot also demonstrates that:

• On the left side, there is a strong positive association between Adjusted Happy Life Years and Ecological Footprint – at low levels of both, improving health and increasing ecological impact go hand in hand. But (and it’s a crucial but) beyond about 75 Adjusted Happy Life Years and four hectares per person there is no improvement in health as the ecological impact increases: trashing the environment isn’t associated with happier, healthier people.
• At any particular level of environmental impact (look at 2-3 gha, for instance), there is an enormous difference in the level of health achieved. This suggests that local circumstances are influencing the relationship between the two, whether that be the natural environment, the country’s history and political economy or current policy settings.

The report also examines the HPI by gender in 11 countries. The consistent pattern was that women had a higher HPI than men (up to eight points higher in some countries) because:

• women had a longer life expectancy (a historically commonly reported observation)
• self-reported wellbeing was almost identical
• men’s ecological footprint was higher.

Two other findings are of interest:

• Countries where the most powerful leader is a woman have an average HPI that is 0.6 per cent higher than where the leader is a man. The authors state that this is in line with other evidence pointing to the importance of women’s leadership in advancing sustainable and inclusive development.
• There is a very weak relationship between GDP and HPI.

The authors conclude that:

• Good lives do not have to cost the Earth. “The transition to sustainability is not about sacrifice, but about redefining what constitutes a good life.”
• Economic growth alone is an unreliable guide to progress and GDP does not measure what matters. “The challenge now is not only to measure what matters, but to make it matter politically.”
• Those with power are often the problem, particularly when they are men. Citizens must be actively involved in defining what a good society looks like.

Regarding a good life, Robert Chesney in 2015 quoted Stephen Hawking on the impact of technology on the future of our species: “[It] will depend entirely on how things are distributed. Everyone can enjoy a life of luxurious leisure if the machine-produced wealth is shared, or most people can end up miserably poor if the machine owners successfully lobby against wealth redistribution. So far the trend seems to be toward the second option, with technology driving ever increasing inequality.”

Chesney then observed: “That’s really the dilemma we face as a people, as a society going forward. Is this economy going to work for us or for them? Are we going to build an economy that fosters the good life for all of us, a democracy, or is it going to be their economy and we’re just sort of extras, if we don’t get in the way.”

Massive underground fungal networks maintain ecosystems

The evidence of a vast underground network of fungi connecting trees to other trees, transporting nutrients around and communicating warnings to each other was not greeted with universal approval when it was first presented. Subsequent research has confirmed the original data and greatly expanded our knowledge about the underground networks of fungi (hyphae) and their functions.

We now know that around three-quarters of plant species form underground associations with arbuscular mycorrhizal (AM) fungi. The fungi penetrate the trees’ roots to form specialised structures (arbuscules) that help the trees absorb water and nutrients in exchange for sugars and carbon received by the fungi. These symbiotic relationships are essential for diverse, healthy above- and below-ground ecosystems and have been extremely beneficial for humans as well by helping the trees absorb some of our profligate carbon emissions.

Lacking has been any detailed understanding of the magnitude of the global hyphal networks and the geographic variations. Machine learning has now been used to predict AM densities around the world using data from over 16,000 soil samples collected in over 300 studies. The magnitude and extent of the subterranean fungal network is astonishing:

• Global topsoils contain about 110 quadrillion kilometres of living hyphae (the Wood Wide Web). That’s almost a billion times the distance between Earth and the sun.
• Together the hyphae weigh four to six times the biomass of humans.
• The tubular networks move about four billion metric tons of carbon each year – equal to about 10 per cent of humanity’s CO2 emissions.
• The density of AM fungi varies greatly around the world. Grasslands account for about 40 per cent of the biomass. Grasslands have vast root systems and, even if the above ground parts are burnt to a cinder, the carbon remains underground and grasslands can recover rapidly, unlike forests.
• AM density is highest along the western seaboard of the Americas, in eastern and southern Africa, and in central Asia. Australia has relatively low AM density except along the east coast. New Zealand is pretty rich with AM. See the maps below.
• Fungal network density is halved in intensively farmed areas.
• Only five per cent of AM diversity hotspots lie in environmentally protected areas.

The brighter yellow areas indicate higher densities of AM fungi.

Separate research in Chile has demonstrated that very old, very large, old-growth trees host over twice as much fungal diversity as younger trees. One 2,400 year-old, 30-m high “grandpa alerce” tree was host to 361 fungal species that were unique to this one tree.

It is postulated that, as trees mature, they need different fungal partners and that the fungal ecosystem helps trees to cope with periods of stress, perhaps with different species of AM supplying different forms of essential assistance at different times, for example during droughts, wildfires and attacks by micro-organisms and insects.

Here’s a radical idea – maybe big, old native trees should be protected from logging? Outrageous, I know – perhaps why no one has thought of it before. Perhaps they also need protecting from humans getting too close to them and disturbing the ecosystem.

When will 1.5^oC be breached?

I’ve been saying for at least a year that the world is certain to scoot past the 1.5^oC upper limit of warming agreed in Paris in 2015 and that this is likely to happen before 2030. If you don’t trust my view, how about the World Meteorological Association’s (WMO) opinion?

The WMO’s recently published Global Annual to Decadal Climate Update 2026-2035 states that in 2025 the global average surface temperature was 1.43^oC above the 1850–1900 baseline, making it one of the three warmest years on record (the others being 2023 and 2024). The last 11 years have been the warmest 11 on record.

The WMO predicts that the global mean temperature during 2026–2030 is likely to continue at record levels and there is a 75 per cent chance that the average over this period will exceed 1.5^oC of warming.

You may recall that President Trump had fun recently with researchers who were proposing that the UN’s future climate scenarios be overhauled, partly because the low-probability, worst-case projection no longer seems relevant. What Trump didn’t say was that the paper’s lead author also stated that, because emissions have increased so much, it is no longer plausible that warming will stay around 1.5^oC with only limited overshoot. Rather, the best-case scenario now sees temperatures overshooting to at least 1.7^oC and even 1.8^oC before returning to 1.5^oC.

I must make clear, in the interests of transparency, that the Paris Agreement’s 1.5^oC limit on warming is based on the average over 20 years, not five; and, for journalistic balance, that some people believe all the carefully collected and analysed, and broadly consistent, evidence on climate change is the work of “Radical Left Dumocrats”.

Which life measures do newspapers tell us are important?

The histogram below (from the Health Planet Index report) plots the number of English language newspaper articles that mentioned each of the indicators of life and social conditions between 1 April 2025 and 31 March 2026. Draw your own conclusions.

The views expressed in this article may or may not reflect those of Pearls and Irritations.