Below is the letter the UN Secretary General sent to all Governments.

Sir,
In my capacity as the depositary of more than six hundred multilateral
treaties, I have the honour to write to encourage the participation of your State in
the 2023 Treaty Event. This initiative, launched in 2000, has proven successful
in the promotion of participation in the multilateral treaty framework of the United
Nations. This year’s Treaty Event will take place from 19 to 22 September 2023,
at United Nations Headquarters in New York, in conjunction with the General Debate
of the seventy-eighth session of the United Nations General Assembly.
The theme of the 2023 Treaty Event will be “Towards universal
participation in multilateral environmental agreements for a healthy planet”.
The success of the recovery of the ozone layer through universal participation
in the Montreal Protocol on Substances that Deplete the Ozone Layer has been
justly celebrated, and I wish to encourage universal participation in all the
multilateral environmental agreements for which I serve as depositary at the
upcoming Treaty Event. The triple crises of climate disruption, biodiversity loss
and pollution destroying our planet require our collective response. The Paris
Agreement on Climate Change, the Kigali Amendment to the Montreal Protocol,
the Convention on Biological Diversity, and others, are among the multilateral
environmental agreements highlighted this year which aim to address these global
concerns. A list of highlighted treaties is enclosed for your consideration.
I wish to extend my invitation for your State to make use of the Treaty
Event by signing on to the highlighted treaties, and by depositing instruments of
ratification or accession to those treaties.
UNITED NATIONS | NATIONS UNIES | PAGE 2
Let me emphasize that the Treaty Event may be used to take action,
not only on the treaties referred to above, but also on any other treaty of which
I am the depositary. They cover a diversity of areas, such as the protection of
human rights, including gender equality, the law of the sea, and disarmament.
A complete list of the multilateral treaties deposited with me is available on the
website of the Treaty Section of the Office of Legal Affairs
(https://treaties.un.org).
Should your State wish to participate in the 2023 Treaty Event, I would be
grateful if you could inform the Treaty Section of the Office of Legal Affairs, by
8 September 2023, of your intention to sign, ratify or accede to any of the treaties
of which I am the depositary, so that the necessary arrangements may be made.
Please accept, Sir, the assurances of my highest consideration.
António Guterres