Fungi are neither plant nor animal. They feed the world's forests, tax every harvest,
and kill more people each year than tuberculosis and malaria combined — and we have barely started
writing down their names.
94%
Species without a name
About 155,000 fungal species have been formally described. Roughly 2.5 million are
thought to exist. Nearly the whole kingdom is uncatalogued.
Niskanen et al., Annual Review of Environment and Resources, 2023
01 — The Census
A kingdom with almost no catalogue
Two centuries of mycology have named roughly one fungal species in sixteen. Even where DNA
sequencing finds them, most are logged as "dark taxa" — real organisms, detected and counted, but never
formally described or given a scientific name.
Sources: Niskanen et al., Annual Review of Environment and Resources (2023);
van Galen et al., Current Biology (2025).
02 — The Thermal Line
Why 37 °C is a wall
Tens of thousands of fungi infect insects, amphibians and reptiles. Only a few hundred can
touch a mammal — because most fungi simply cannot grow at our body temperature. Measurements across
thousands of species show that for every 1 °C above 30 °C, about 6% fewer fungal species can still grow.
Warm blood is an antifungal shield, and a narrow one.
Sources: Robert & Casadevall, Journal of Infectious Diseases (2009);
Bergman & Casadevall, mBio (2010).
The strip's gradient is an illustrative rendering of the measured ~6%-per-°C decline, not a measured curve.
03 — The Underground Pipe
Plants pay their fungi in carbon
Land plants route between 1% and 13% of the carbon they fix straight down into the mycorrhizal
fungi wrapped around their roots, in exchange for water and minerals. Summed globally, that private
transaction moves an estimated 13.12 gigatonnes of CO₂-equivalent underground every year — about
36% of what fossil fuels emit.
Source: Hawkins et al., "Mycorrhizal mycelium as a global carbon pool," Current Biology (2023),
a meta-analysis of ~200 datasets.
The authors flag these as first-order global estimates to be read with caution.
04 — The Harvest Tax
A tenth to a quarter of every harvest
Fungi are the most important agents of plant disease on Earth. Even with fungicides applied,
growers lose 10–23% of their crops in the field to fungal infection, and another 10–20% after harvest.
Across the five great calorie crops — rice, wheat, maize, soybean and potato — that is enough food to give
between 600 million and 4 billion people 2,000 calories a day for a year.
Source: Stukenbrock & Gurr, "Address the growing urgency of fungal disease in crops,"
Nature (2023). Fungal crop pathogens have also shifted poleward at roughly 7 km a year since 1960
(Bebber et al., Nature Climate Change, 2013), and some spores stay viable in soil for up to 40 years.
05 — The Quiet Killer
3.8 million deaths a year
The first full global accounting of severe fungal disease, published in 2024, counted about
6.5 million invasive fungal infections a year and 3.8 million associated deaths — roughly 2.5 million of
them directly attributable to the fungus. That is more than tuberculosis and malaria put together, from a
disease group with no vaccine and four drug classes.
Sources: Denning, "Global incidence and mortality of severe fungal disease,"
The Lancet Infectious Diseases (2024); WHO Global Tuberculosis Report (2025);
WHO World Malaria Report (2024). Fungal totals also include ~46,000 deaths a year linked to fungal asthma.
6.5M
Invasive fungal infections a year
4
Classes of antifungal drug in clinical use
19
Fungi on the WHO priority pathogens list, 2022
06 — The Resistance Curve
One fungus, eight years
Candida auris was unknown to science until 2009. It resists disinfectants, survives on
hospital surfaces for weeks, and increasingly shrugs off echinocandins — the first-line drug. US clinical
cases have risen every single year since surveillance began.
Sources: Lyman et al., Annals of Internal Medicine (2023) for 2019–21;
CDC, "Surveillance for Candida auris — United States, 2022–2024," MMWR Surveillance Summaries (2026)
for 2022–24. Counts are cases reported to CDC and reflect testing effort as well as spread.
07 — The Warming Edge
The wall is getting lower
If 37 °C is the barrier that keeps most fungi out of us, a hotter world narrows the gap two
ways at once: it selects for fungi that tolerate heat, and it widens the map where the dangerous ones can
live. Meanwhile, the azole fungicides sprayed on fields are chemical cousins of the azole drugs used in
hospitals — resistance learned in a wheat field can arrive in a lung.
+77.5%
Projected growth in European habitat suitable for Aspergillus fumigatus by 2100 — modelled, high-emissions scenario
9M
Additional people in Europe projected to be exposed — modelled
7 km
Average poleward shift of fungal crop pathogens per year since 1960
Source: van Rhijn et al., University of Manchester / Wellcome (2025), species-distribution
modelling of Aspergillus fumigatus, A. flavus and A. niger.
These are model projections, not observations.
Why it matters
We are managing a kingdom we haven't finished counting
Fungal disease is under-diagnosed, not rare. Most of the 3.8 million annual deaths follow another
illness — cancer treatment, HIV, ICU care, severe flu or COVID. Access to basic fungal diagnostics is the
single biggest lever, and it is missing across much of the world.
Four drug classes is not a pipeline. Antifungals are hard to design because fungal cells are
biochemically close to ours. Every new class matters; so does not wasting the ones we have.
Farm chemistry and hospital chemistry are the same chemistry. Rotating fungicide modes of action
in agriculture protects human medicines, not just yields.
Soil is infrastructure. The mycorrhizal networks moving ~13 Gt CO₂e a year sit almost entirely
outside conservation planning — and 83% of the species involved don't yet have names to protect.
Name them. Fungal taxonomy is small, cheap science with outsized returns: you cannot regulate,
conserve or treat an organism that has no name.
Sources & notes
Niskanen, T. et al. "Pushing the Frontiers of Biodiversity Research: Unveiling the Global Diversity,
Distribution, and Conservation of Fungi." Annual Review of Environment and Resources, 2023.
— ~155,000 described species of an estimated ~2.5 million.
van Galen, L.G. et al. "Ectomycorrhizal fungi." Current Biology 35(11), 2025.
— 83% of ectomycorrhizal species are undescribed "dark taxa."
Robert, V.A. & Casadevall, A. "Vertebrate Endothermy Restricts Most Fungi as Potential Pathogens."
The Journal of Infectious Diseases, 2009. — ~6% fewer species grow per +1 °C above 30 °C.
Bergman, A. & Casadevall, A. "Mammalian Endothermy Optimally Restricts Fungi and Metabolic Costs."
mBio, 2010. — optimum modelled at 36.7 °C.
[MODELLED]
Hawkins, H.-J. et al. "Mycorrhizal mycelium as a global carbon pool." Current Biology, 2023.
— 13.12 Gt CO₂e/yr total (9.07 ecto, 3.93 arbuscular, 0.12 ericoid); ≈36% of annual fossil-fuel emissions.
[ESTIMATE — AUTHORS URGE CAUTION]
Stukenbrock, E. & Gurr, S. "Address the growing urgency of fungal disease in crops."
Nature 617, 2023. — 10–23% in-field and 10–20% post-harvest losses; 600 million–4 billion people'
worth of calories.
Bebber, D.P. et al. "Crop pests and pathogens move polewards in a warming world."
Nature Climate Change, 2013. — fungi shifting ~7 km/yr poleward since 1960.
Denning, D.W. "Global incidence and mortality of severe fungal disease."
The Lancet Infectious Diseases 24, 2024. — 6.5M invasive infections, 3.8M deaths,
~2.5M (68%; range 35–90%) directly attributable; per-disease figures as charted.
World Health Organization.WHO Fungal Priority Pathogens List, 2022.
— 19 priority fungi; four antifungal drug classes in clinical use.
Lyman, M. et al. "Worsening Spread of Candida auris in the United States, 2019 to 2021."
Annals of Internal Medicine, 2023. — 476 / 756 / 1,471 clinical cases.
CDC. "Surveillance for Candida auris — United States, 2022–2024."
MMWR Surveillance Summaries, 2026. — 2,882 / 4,428 / 6,197 clinical cases; 13,507 total.
2016 first-year count (53) from CDC tracking.
van Rhijn, N. et al. University of Manchester / Wellcome, 2025 (preprint).
— Aspergillus fumigatus European range +77.5% and ~9 million more people exposed under SSP5-8.5 by 2100.
[MODELLED PROJECTION]
WHO.Global Tuberculosis Report 2025 (1.23M deaths, 2024) and
World Malaria Report 2024 (597,000 deaths, 2023) — comparison figures only.