You're certainly correct, but brevity of the writer and intelligence of the reader means I don't have to be explicit about every point, just as if I were to write that a cockpit altitude alarm is telling a pilot he must act with increasing urgency to pull a plane up from a perilous dive.
I could be explicit, and say that the alarm itself is just a combination of electrical circuitry and detectors that change behaviour due to input thresholds, and that the alarm does not particularly care whether the plane crashes or not, but I trust that the reader understands what I'm saying when I say the alarm is telling the pilot he must pull up.
When it comes to declaring what science tells us we "must" do, the picture is far less clear. One reason to be explicit about the difference between "is" and "must" is that even intelligent readers and writers sometimes hold mistaken beliefs here. Another reason is that, even among those in total agreement about the science and in total agreement about certain predictions, there is still disagreement about whether various tradeoffs are "worth" the cost. At that point, science is simply the wrong tool to tell us what we "must" do.
Forgive me for this meta-detour, but:
Science tells us that the climate is changing in ways that most of humanity would consider harmful. Science tells us that carbon emissions are one of the major drivers of those changes. Science tells us what we can expect to happen if we take certain courses of action. But science doesn't tell us what we "must" do or what course of action we "must" take; science only tells us "is".
"Must" is necessarily a matter of ethics, philosophy, politics, or religion. Science doesn't tell us what course of action is better or worse, only what the expected outcomes are. Things-other-than-science are how we determine what we mean by "better" or "worse" (for an extreme example, consider that some people want humanity to go extinct; their idea of "better" and my idea of "better" do not remotely resemble each other.)