The pathway for transforming global energy systems to reach net-zero emissions by 2050 is "narrow but still achievable" and demands unprecedented acceleration away from fossil fuels, an International Energy Agency report published Tuesday concludes.

Why it matters: It provides detailed analysis and estimates of what's needed for a good shot at limiting temperature rise to 1.5°C above preindustrial levels — the Paris Agreement benchmark for avoiding some of the most damaging effects of climate change.

Threat level: The IEAoffers frank assessments of the closing window to keep 1.5°C in sight, but also data-backed arguments for why this immensely heavy lift is cost-effectively achievable.

• Current national targets — even leaving aside the absence of policies to meet them — would still leave 22 billion tons of CO2 emissions in 2050, the IEA projects.
• Global greenhouse gas emissions and fossil fuel consumption are nowhere near on pace for meeting a net-zero mid-century goal.
• Emissions are rebounding strongly from the pandemic-fueled drop and "further delay in acting to reverse that trend will put net zero by 2050 out of reach."

The big picture: The first-time report uses a "hybrid modeling approach" to explore needed uptake of renewables, hydrogen and other tech.

• It fuses methods from the IEA's annual long-term projections called the World Energy Outlook, and its Energy Technology Perspectives series that analyzes hundreds of technologies.

Key findings: "Beyond projects already committed as of 2021, there are no new oil and gas fields approved for development in our pathway," the report notes.

• New coal mines or extensions are also inconsistent with the IEA's net-zero pathway.
• Sales of new internal combustion engine cars would need to end by 2035.

What's next: A lot of changes have to happen really fast to keep the narrow net-zero pathway open.

• Energy efficiency would have to increase a lot. The net-zero pathway envisions 4% average annual improvements in energy intensity — that is, energy per unit of economic output.
• The report envisions annual additions of 630 gigawatts of solar photovoltaic generating capacity and 390 GW by 2030 — four times the record levels installed last year.

While the report is pretty clear-eyed about the difficulty of a net-zero pathway, one bright spot is the IEA's take on how much is possible with existing technology — at least in the medium term.

• "Most of the global reductions in CO2 emissions through 2030 in our pathway come from technologies readily available today," the IEA states.
• However, "in 2050, almost half the reductions come from technologies that are currently at the demonstration or prototype phase."

The bottom line: "The scale and speed of the efforts demanded by this critical and formidable goal — our best chance of tackling climate change and limiting global warming to 1.5°C — make this perhaps the greatest challenge humankind has ever faced," IEA executive director Fatih Birol said in a statement.